FAIR VALUES OF FINANCIAL INSTRUMENTS - Reconciliation of Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 52,567	$ 34,198	$ 49,939	$ 19,082
Transfers in and (out) of Level 3 (1)	0	0	0	0
Total gains or losses (realized/unrealized):
Included in earnings—fair value adjustment	(465)	(3,097)	(14,497)	(2,087)
Additions	14,300	12,143	35,648	36,034
Sales, paydowns, and other	(3,726)	(2,407)	(8,414)	(12,192)
Balance at end of period	62,676	40,837	62,676	40,837
Agency mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	34,251	0	18,291	0
Transfers in and (out) of Level 3 (1)	0	0	0	0
Total gains or losses (realized/unrealized):
Included in earnings—fair value adjustment	(21)	0	121	0
Additions	14,445	0	35,548	0
Sales, paydowns, and other	(1,027)	0	(6,312)	0
Balance at end of period	$ 47,648	$ 0	$ 47,648	$ 0