| **DERIVATIVES (Tables)**                                                              | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|---------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
||
| **Derivative [Line Items]**                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Impact of Derivative Activities in the Condensed Consolidated Statement of Operations | The following Condensed Consolidated Statement of Operations line items were impacted by the Company’s derivative activities for the three-month and nine-month periods endedSeptember 30, 2015 and 2014, respectively:    Three-Month PeriodEnded September 30,  Nine-Month PeriodEnded September 30,Derivative Activity Accounts 2015 2014 2015 2014    (in thousands)Fair value hedges:          Cross-currency swaps Miscellaneous income immaterial immaterial $110 $774Interest rate swaps Miscellaneous income (3,985) 1,731 (5,437) 978Cash flow hedges:          Pay fixed-receive variable interestrate swaps Net interest income (1,775) (13,469) (9,957) (40,936)Other derivative activities:          Forward commitments to sell loans Mortgage banking income (10,711) 2,490 (1,776) (2,762)Interest rate lock commitments Mortgage banking income 3,595 (2,027) 2,417 1,518Mortgage servicing Mortgage banking income 11,736 1,032 1,302 (4,100)Customer related derivatives Miscellaneous income (1,251) 3,280 (179) 6,941Foreign exchange Miscellaneous income (109) 1,794 (1,973) 1,302SCUSA derivatives Miscellaneous income (3,746) 9,130 711 27,269 Net interest income 21,093 (971) 58,453 (4,951)Other Miscellaneous income (1,649) 580 (2,107) (729)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
| Offsetting Assets                                                                     | Information about financial assets and liabilities that are eligible for offset on the Condensed Consolidated Balance Sheet as of September 30, 2015 and December 31, 2014, respectively, is presented in the following tables:  Offsetting of Financial Assets         Gross Amounts Not Offset in the Condensed Consolidated Balance Sheet  Gross Amounts of Recognized Assets Gross Amounts Offset in the Condensed Consolidated Balance Sheet Net Amounts of Assets Presented in the Condensed Consolidated Balance Sheet Financial Instruments Cash Collateral Received Net Amount  (in thousands)September 30, 2015            Fair value hedges $3,708 $— $3,708 $— $— $3,708Cash flow hedges — — — — — —Other derivative activities(1) 415,236 9,015 406,221 8,027 45,306 352,888Total derivatives subject to a master netting arrangement or similar arrangement 418,944 9,015 409,929 8,027 45,306 356,596Total derivatives not subject to a master netting arrangement or similar arrangement(2) 5,480 — 5,480 — — 5,480Total Derivative Assets $424,424 $9,015 $415,409 $8,027 $45,306 $362,076             Total Financial Assets  $424,424 $9,015 $415,409 $8,027 $45,306 $362,076             December 31, 2014            Fair value hedges $2,943 $— $2,943 $— $— $2,943Cash flow hedges 7,619 — 7,619 — — 7,619Other derivative activities(1) 373,545 21,109 352,436 10,020 5,940 336,476Total derivatives subject to a master netting arrangement or similar arrangement 384,107 21,109 362,998 10,020 5,940 347,038Total derivatives not subject to a master netting arrangement or similar arrangement(2) 3,063 — 3,063 — — 3,063Total Derivative Assets $387,170 $21,109 $366,061 $10,020 $5,940 $350,101             Total Financial Assets  $387,170 $21,109 $366,061 $10,020 $5,940 $350,101(1)Includes customer-related and other derivatives(2)Includes mortgage banking derivatives |
| Offsetting Liabilities                                                                |   Offsetting of Financial Liabilities        Gross Amounts Not Offset in the Condensed Consolidated Balance Sheet  Gross Amounts of Recognized Liabilities Gross Amounts Offset in the Condensed Consolidated Balance Sheet Net Amounts of Liabilities Presented in the Condensed Consolidated Balance Sheet Financial Instruments Cash Collateral Pledged Net Amount  (in thousands)September 30, 2015            Fair value hedges $6,445 $— $6,445 $114 $12,703 $(6,372)Cash flow hedges 71,178 39,108 32,070 — 40,329 (8,259)Other derivative activities(1) 397,158 134,386 262,772 8,016 187,454 67,302Total derivatives subject to a master netting arrangement or similar arrangement 474,781 173,494 301,287 8,130 240,486 52,671Total derivatives not subject to a master netting arrangement or similar arrangement(2) 368 — 368 — — 368Total Derivative Liabilities  $475,149 $173,494 $301,655 $8,130 $240,486 $53,039             Total Financial Liabilities $475,149 $173,494 $301,655 $8,130 $240,486 $53,039             December 31, 2014            Fair value hedges $1,759 $— $1,759 $65 $5,589 $(3,895)Cash flow hedges 20,552 — 20,552 7,341 16,797 (3,586)Other derivative activities(1) 350,863 21,109 329,754 49,318 198,103 82,333Total derivatives subject to a master netting arrangement or similar arrangement 373,174 21,109 352,065 56,724 220,489 74,852Total derivatives not subject to a master netting arrangement or similar arrangement(2) 1,817 — 1,817 — 1,736 81Total Derivative Liabilities  $374,991 $21,109 $353,882 $56,724 $222,225 $74,933             Total Financial Liabilities $374,991 $21,109 $353,882 $56,724 $222,225 $74,933(1)Includes customer-related and other derivatives(2)Includes mortgage banking derivatives                                                                                                                                                                                                                   |
| Designated as hedging instrument                                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| **Derivative [Line Items]**                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Schedule of Derivative Instruments                                                    | Derivatives designated as accounting hedges at September 30, 2015 and December 31, 2014 included: NotionalAmount Asset Liability Weighted Average ReceiveRate Weighted Average PayRate Weighted Average  Life(Years) (dollars in thousands)September 30, 2015           Fair value hedges:           Cross-currency swaps$16,757 $3,555 $309 4.76% 4.75% 0.36Interest rate swaps318,000 153 6,136 1.00% 2.29% 3.75Cash flow hedges:           Pay fixed — receive floating interest rate swaps10,751,056 — 71,178 0.20% 1.09% 3.12Total$11,085,813 $3,708 $77,623 0.23% 1.13% 3.13            December 31, 2014           Fair Value hedges:           Cross-currency swaps$18,230 $2,711 $980 4.76% 4.75% 1.11    Interest rate swaps257,000 232 779 0.90% 2.38% 4.33Cash flow hedges:           Pay fixed — receive floating interest rate swaps10,086,103 7,619 20,552 0.17% 1.11% 3.02Total$10,361,333 $10,562 $22,311 0.19% 1.14% 3.05                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
| Not designated as hedging instrument                                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| **Derivative [Line Items]**                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Schedule of Other Derivative Activities                                               | Other derivative activities at September 30, 2015 and December 31, 2014 included: Notional Asset derivativesFair value Liability derivativesFair value September 30, 2015 December 31, 2014 September 30, 2015 December 31, 2014 September 30, 2015 December 31, 2014 (in thousands)Mortgage banking derivatives:           Forward commitments to sell loans$482,207 $328,757 $— $— $4,200 $2,424Interest rate lock commitments248,375 163,013 5,480 3,063 — —Mortgage servicing435,000 469,000 3,684 7,432 2,399 7,448Total mortgage banking risk management1,165,582 960,770 9,164 10,495 6,599 9,872            Customer related derivatives:           Swaps receive fixed8,624,004 7,927,522 300,848 213,415 1,194 4,343Swaps pay fixed8,749,748 7,944,247 3,306 13,361 267,923 186,732Other2,983,761 1,670,696 44,899 62,464 43,931 61,880Total customer related derivatives20,357,513 17,542,465 349,053 289,240 313,048 252,955            Other derivative activities:           Foreign exchange contracts2,136,160 1,152,125 29,413 20,033 28,743 17,390Interest rate swap agreements2,833,000 3,231,000 — 535 12,743 12,743Interest rate cap agreements9,211,000 7,541,385 24,451 49,762 — —Options for interest rate cap agreements9,211,000 7,541,385 — — 24,462 49,806Other822,534 646,321 8,635 6,543 11,931 9,914Total$45,736,789 $38,615,451 $420,716 $376,608 $397,526 $352,680                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |

| X                                                                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.
+ References
No definition available.
+ Details**Name:**us-gaap_DerivativeLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tabular disclosure of derivative and other financial assets that are subject to offsetting, including master netting arrangements.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225877-175312
+ Details**Name:**us-gaap_OffsettingAssetsTableTextBlock**Namespace Prefix:**us-gaap_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tabular disclosure of derivative and other financial liabilities that are subject to offsetting, including master netting arrangements.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225877-175312Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312
+ Details**Name:**us-gaap_OffsettingLiabilitiesTableTextBlock**Namespace Prefix:**us-gaap_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tabular disclosure of the location and amount of derivative instruments and nonderivative instruments designated as hedging instruments reported before netting adjustments, and the amount of gain (loss) on derivative instruments and nonderivative instruments designated and qualified as hedging instruments.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5618551-113959
+ Details**Name:**us-gaap_ScheduleOfDerivativeInstrumentsGainLossInStatementOfFinancialPerformanceTextBlock**Namespace Prefix:**us-gaap_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tabular disclosure of the location and fair value amounts of derivative instruments (and nonderivative instruments that are designated and qualify as hedging instruments) reported in the statement of financial position.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959
+ Details**Name:**us-gaap_ScheduleOfDerivativeInstrumentsInStatementOfFinancialPositionFairValueTextBlock**Namespace Prefix:**us-gaap_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=56946850&loc=d3e41641-113959Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=56946850&loc=d3e41678-113959Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=56946850&loc=d3e41638-113959Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5580258-113959Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5579245-113959Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 25 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6886632&loc=d3e76258-113986Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5579240-113959Reference 10: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=56946850&loc=d3e41620-113959Reference 11: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(n)(2)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690
+ Details**Name:**us-gaap_ScheduleOfDerivativeInstrumentsTextBlock**Namespace Prefix:**us-gaap_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                  |
|----------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |