SEGMENT INFORMATION - Reconciliation of Reportable Segment Financial Information (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Net Income (Loss):
Segment income		$ 62,896	$ 52,779	$ 105,766	$ 106,957
Other operating expenses	[1]	(25,608)	(23,303)	(51,010)	(48,414)
Income before income taxes		37,288	29,476	54,756	58,543
Income tax expense		(9,290)	(7,523)	(1,217)	(13,246)
Total consolidated net income (loss)		27,998	21,953	53,539	45,297
Average assets:
Total average earning assets for segments		10,980,018	11,769,157	10,987,048	11,736,912
Average non-earning assets		900,622	972,711	893,785	961,237
Total consolidated average assets		$ 11,880,640	$ 12,741,868	$ 11,880,833	$ 12,698,149

[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.