PREMISES AND EQUIPMENT, NET (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	$ 222,279		$ 232,693
Total premises and equipment, net	74,991		45,631
Depreciation and amortization expense	9,369	$ 8,721
Computer hardware and software
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	177,868		182,215
Office equipment and other
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	5,264		7,384
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	12,222		13,313
Leasehold improvements
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	26,925		29,781
Excluding Right-to-use Assets
Property, Plant and Equipment [Line Items]
Less: Accumulated depreciation and amortization	(182,882)		(187,062)
Total premises and equipment, net	39,397		$ 45,631
Right-to-use Assets
Property, Plant and Equipment [Line Items]
Premises and equipment, gross	39,046
Less: Accumulated depreciation and amortization	(3,452)
Total premises and equipment, net	$ 35,594