SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE - Schedule of Repurchase Agreement Maturity (Detail) - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Repurchase Agreement [Line Items]
Securities Sold Under Agreements To Repurchase	[1],[2]	$ 700,000	$ 700,000
Less than three years
Repurchase Agreement [Line Items]
Securities Sold Under Agreements To Repurchase		100,000
Over five years
Repurchase Agreement [Line Items]
Securities Sold Under Agreements To Repurchase		200,000
Securities Sold Under Agreements To Repurchase Mature Over Three Months To One Year [Member]
Repurchase Agreement [Line Items]
Securities Sold Under Agreements To Repurchase		$ 400,000

[1] As of March 31, 2016, includes $600 million with an average rate of 2.88% that lenders have the right to call before their contractual maturities at various dates beginning on July 19, 2016. Subsequent to March 31, 2016, no lender has exercised its call option on repurchase agreements. In addition, $500 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.