PREMISES AND EQUIPMENT, NET (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	$ 232,870,000	$ 248,676,000
Less: accumulated depreciation and amortization	(129,397,000)	(129,555,000)
Total	103,473,000	119,121,000
Depreciation and amortization expense	36,788,000	36,470,000	$ 29,046,000
Impairment of premises and equipment	0	4,122,000	$ 0
Computer hardware and software
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	164,877,000	177,010,000
Office equipment and other
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	20,188,000	21,720,000
Furniture and fixtures
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	13,997,000	14,443,000
Leasehold improvements
PREMISES AND EQUIPMENT, NET
Premises and equipment, gross	$ 33,808,000	$ 35,503,000