SEGMENT INFORMATION - Reconciliation of Reportable Segment Financial Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income (Loss):
Segment income		$ 7,122	$ 59,419	$ 112,888	$ 166,376
Other operating expenses	[1]	(26,272)	(24,901)	(77,282)	(73,315)
(Loss) income before income taxes		(19,150)	34,518	35,606	93,061
Income tax benefit (expense)		8,398	(10,444)	7,181	(23,690)
Net income		(10,752)	24,074	42,787	69,371
Average assets:
Total average earning assets for segments		11,083,964	11,354,259	11,019,249	11,631,135
Average non-earning assets		900,334	926,043	896,071	927,732
Total consolidated average assets		$ 11,984,298	$ 12,280,302	$ 11,915,320	$ 12,558,867

[1] Expenses pertaining to corporate administrative functions that support the operating segments but are not specifically attributable to or managed by any segment are not included in the reported financial results of the operating segments. The unallocated corporate expenses include certain general and administrative expenses and related depreciation and amortization expenses.