INCOME TAXES - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets:
Compensation related	$ 14,320	$ 17,341
Credit losses	959	1,269
Other	149	407
Total deferred tax assets	15,428	19,017
Deferred Tax Liabilities:
Mark-to-market of derivatives and loans held for sale	(4,389)	(19,934)
Mortgage servicing rights related	(115,239)	(135,519)
Acquisition related	(2,323)	(722)
Depreciation	(1,536)	(1,862)
Total deferred tax liabilities	(123,487)	(158,037)
Deferred tax liabilities, net	$ (108,059)	$ (139,020)