SEGMENT INFORMATION - Reconciliation of Reportable Segment Financial Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net Income (Loss):
Income before income taxes	$ 60,932	$ 40,906
Income tax expense	17,618	7,758
Net income	43,314	33,148
Segment Reconciling Items [Member]
Net Income (Loss):
Total income for segments and other	87,205	69,072
Other operating expenses	(26,273)	(28,166)
Income before income taxes	60,932	40,906
Income tax expense	17,618	7,758
Net income	43,314	33,148
Average assets:
Total average earning assets for segments	11,280,192	11,244,444
Average non-earning assets	1,003,706	947,460
Total consolidated average assets	$ 12,283,898	$ 12,191,904