|**DEPOSITS AND OTHER CUSTOMER ACCOUNTS** | 9 Months Ended                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             
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|**Deposits [Abstract]**                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|DEPOSITS AND OTHER CUSTOMER ACCOUNTS     | DEPOSITS AND OTHER CUSTOMER ACCOUNTSDeposits and other customer accounts are summarized as follows:September 30, 2018December 31, 2017(dollars in thousands)BalancePercent of total depositsBalancePercent of total depositsInterest-bearing demand deposits$8,154,38013.4%$8,784,59714.4%Non-interest-bearing demand deposits15,075,15324.7%15,402,23525.3%Savings5,889,8339.7%5,903,8979.7%Customer repurchase accounts550,3570.9%802,1191.4%Money market24,956,35541.0%24,530,66140.3%CDs6,315,91910.3%5,407,5948.9%Total Deposits(1)$60,941,997100.0%$60,831,103100.0%(1)Includes foreign deposits, as defined by the FRB, of$8.6 billionand$9.1 billionatSeptember 30, 2018andDecember 31, 2017, respectively.Deposits collateralized by investment securities, loans, and other financial instruments totaled$2.5 billionand$2.3 billionatSeptember 30, 2018andDecember 31, 2017, respectively.Demand deposit overdrafts that have been reclassified as loan balances were$119.3 millionand$38.9 millionatSeptember 30, 2018andDecember 31, 2017, respectively.AtSeptember 30, 2018andDecember 31, 2017, the Company had$1.6 billionand$1.3 billionof CDs greater than $250 thousand.
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|(dollars in thousands)                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|Interest-bearing demand deposits         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|Non-interest-bearing demand deposits     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|Savings                                  |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|Customer repurchase accounts             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|Money market                             |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|CDs                                      |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
|Total Deposits(1)                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
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|(1)                                      | Includes foreign deposits, as defined by the FRB, of$8.6 billionand$9.1 billionatSeptember 30, 2018andDecember 31, 2017, respectively.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     

X- DefinitionThe entire disclosure for deposit liabilities including data and tables. It may include a description of the entity's deposit liabilities, the aggregate amount of time deposits (including certificates of deposit) in denominations of $100,000 or more at the balance sheet date; the aggregate amount of any demand deposits that have been reclassified as loan balances, such as overdrafts, at the balance sheet date; deposits that are received on terms other than those in the normal course of business, the amount of accrued interest on deposit liabilities; securities, mortgage loans or other financial instruments that serve as collateral for deposits; for time deposits having a remaining term of more than one year, the aggregate amount of maturities for each of the five years following the balance sheet date; and the weighted average interest rate for all deposit liabilities held by the entity.
+ ReferencesReference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 405 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=50488274&loc=d3e64164-112818Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.12) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878
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