LOANS AND ALLOWANCE FOR CREDIT LOSSES (Non-accrual Loans) (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Non-accrual loans	$ 1,455,437	$ 2,173,052
Non-accrual loans with no allowance	461,884
Interest Income recognized on nonaccrual loans	62,572
Foreclosed and other repossessed assets	133,577	217,184
Nonperforming
Financing Receivable, Past Due [Line Items]
OREO	53,258	66,828
Repossessed vehicles	131,309	212,966
Foreclosed and other repossessed assets	2,268	4,218
Total OREO and other repossessed assets	186,835	284,012
Total non-performing assets	1,642,272	2,457,064
Commercial
Financing Receivable, Past Due [Line Items]
Non-accrual loans	280,337	273,644
Non-accrual loans with no allowance	155,085
Interest Income recognized on nonaccrual loans	0
Commercial \| CRE
Financing Receivable, Past Due [Line Items]
Non-accrual loans	110,814	83,117
Non-accrual loans with no allowance	62,960
Interest Income recognized on nonaccrual loans	0
Commercial \| C&I
Financing Receivable, Past Due [Line Items]
Non-accrual loans	92,895	153,428
Non-accrual loans with no allowance	40,875
Interest Income recognized on nonaccrual loans	0
Commercial \| Multifamily
Financing Receivable, Past Due [Line Items]
Non-accrual loans	60,188	5,112
Non-accrual loans with no allowance	45,460
Interest Income recognized on nonaccrual loans	0
Commercial \| Other commercial
Financing Receivable, Past Due [Line Items]
Non-accrual loans	16,440	31,987
Non-accrual loans with no allowance	5,790
Interest Income recognized on nonaccrual loans	0
Consumer
Financing Receivable, Past Due [Line Items]
Non-accrual loans	1,175,100	1,899,408
Non-accrual loans with no allowance	306,799
Interest Income recognized on nonaccrual loans	62,572
Consumer \| Residential mortgages
Financing Receivable, Past Due [Line Items]
Non-accrual loans	147,931	134,957
Non-accrual loans with no allowance	77,568
Interest Income recognized on nonaccrual loans	0
Consumer \| Home equity loans and lines of credit
Financing Receivable, Past Due [Line Items]
Non-accrual loans	110,917	107,289
Non-accrual loans with no allowance	41,415
Interest Income recognized on nonaccrual loans	0
Consumer \| RICs and auto loans
Financing Receivable, Past Due [Line Items]
Non-accrual loans	903,290	1,643,459
Non-accrual loans with no allowance	187,368
Interest Income recognized on nonaccrual loans	62,572
Consumer \| Personal unsecured loans
Financing Receivable, Past Due [Line Items]
Non-accrual loans	2,801	2,212
Non-accrual loans with no allowance	367
Interest Income recognized on nonaccrual loans	0
Consumer \| Other consumer
Financing Receivable, Past Due [Line Items]
Non-accrual loans	10,161	$ 11,491
Non-accrual loans with no allowance	81
Interest Income recognized on nonaccrual loans	$ 0

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