PREMISES AND EQUIPMENT, NET (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 95,464		$ 95,464		$ 181,187
Less: Accumulated depreciation and amortization	(80,481)		(80,481)		(156,661)
Total	14,983		14,983		24,526
Depreciation and amortization expense	3,800	$ 3,700	11,500	$ 14,200
Computer hardware and software
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	68,242		68,242		144,608
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	17,857		17,857		23,800
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	6,553		6,553		8,775
Office equipment and other
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 2,812		$ 2,812		$ 4,004