SECURITIES SOLD UNDER AGREEMENTS TO REPURCHASE - Schedule of Repurchase Agreement Maturity (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Repurchase Agreement [Line Items]
Securities Sold Under Agreements To Repurchase	$ 900,000	[1]	$ 900,000	[1]

[1] As of March 31, 2015, includes $800 million with an average rate of 2.71% that lenders have the right to call before their contractual maturities at various dates beginning on April 9, 2015. Subsequent to April 9, 2015, no lender has exercised its call option on repurchase agreements. In addition, $700 million is tied to variable rates.