SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE - Narratives (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Weighted-average interest rates on repurchase agreements		2.35%	2.73%
Maximum aggregate balance outstanding	[1],[2]	$ 300,000	$ 700,000
Gain Loss On Sale Of Securities Net		6,104	0	$ 262
Repurchase Agreements [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Accrued interest payable on repurchase agreements		$ 1,900	$ 4,000
Weighted average interest rate		3.28%	2.92%
Callable Repurchase Agreements [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Weighted-average interest rates on repurchase agreements		2.11%
Maximum [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Weighted-average interest rates on repurchase agreements		2.83%	3.41%
Maximum aggregate balance outstanding		$ 700,000	$ 900,000
Weighted Average [Member]
Securities Sold Under Agreements To Repurchase And Other Short Term Borrowings [Line Items]
Average balance outstanding		$ 616,400	$ 769,000

[1] As of December 31, 2016, includes $200 million that have an average rate of 2.11% and that are callable by lenders before their contractual maturities at various dates beginning on January 19, 2017. Subsequent to December 31, 2016, no lender has exercised its call option on repurchase agreements. In addition, $100 million is tied to variable rates.

[2] Reported net of securities purchased under agreements to repurchase (reverse repurchase agreements) by counterparty, when applicable, pursuant to ASC 210-20-45-11.