PREMISES AND EQUIPMENT, NET (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	$ 237,846		$ 237,846		$ 236,464
Less: Accumulated depreciation and amortization	(179,026)		(179,026)		(163,191)
Total	58,820		58,820		73,273
Depreciation and amortization expense	8,300	$ 8,900	17,049	$ 18,895
Computer hardware and software
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	182,606		182,606		179,567
Leasehold improvements
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	32,658		32,658		33,417
Furniture and fixtures
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	13,695		13,695		14,092
Office equipment and other
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	$ 8,887		$ 8,887		$ 9,388