INVESTMENT SECURITIES - Proceeds from Sales and Calls of Securities and Associated Gross Gains and Losses (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Schedule of Available-for-sale Securities [Line Items]
Net realized gains on sales and calls of securities available-for-sale	$ 487	$ 1,750	$ 30,100	$ 1,748
Proceeds from sales and calls of securities available-for-sale	232,512	403,032	3,783,965	403,206
Tax expense on sales and calls of securities available-for-sale	202	736	12,507	735
Debt Securities
Schedule of Available-for-sale Securities [Line Items]
Gross realized gains on sales and calls of securities available-for-sale	487	1,750	30,105	1,750
Gross realized losses on sales and calls of securities available-for-sale	0	0	(5)	(2)
Net realized gains on sales and calls of securities available-for-sale	$ 487	$ 1,750	$ 30,100	$ 1,748