| **GOODWILL AND OTHER INTANGIBLES (Goodwill) (Details) - USD ($) $ in Thousands** | Mar. 31, 2020 | Dec. 31, 2019 |
|----------------------------------------------------------------------------------|---------------|---------------|
| **Goodwill [Line Items]**                                                        |          |          |
| Goodwill                                                                         | $ 4,444,389   | $ 4,444,389   |
| CBB                                                                              |          |          |
| **Goodwill [Line Items]**                                                        |          |          |
| Goodwill                                                                         | 1,880,304     |          |
| C&I                                                                          |          |          |
| **Goodwill [Line Items]**                                                        |          |          |
| Goodwill                                                                         | 317,924       |          |
| CRE & VF                                                                     |          |          |
| **Goodwill [Line Items]**                                                        |          |          |
| Goodwill                                                                         | 1,095,071     |          |
| CIB                                                                              |          |          |
| **Goodwill [Line Items]**                                                        |          |          |
| Goodwill                                                                         | 131,130       |          |
| SC                                                                               |          |          |
| **Goodwill [Line Items]**                                                        |          |          |
| Goodwill                                                                         | $ 1,019,960   |          |

| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.
+ References
Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266
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| 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.
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