DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS - Fair Value and Related Disclosures for Debt Securities (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Residential Mortgage Securities Classified as held-to-Maturity [Member]
Held-to-maturity securities disclosure [Abstract]
Held-to-maturities, Amortized Cost Basis	$ 4,275	$ 4,376
Held-to-maturities, Gains	203	211
Held-to-maturities, Losses	0	0
Held-to-maturities, Fair Value	4,478	4,587
Fannie Mae/Freddie Mac [Member] | Agency Securities Classified as Available-for-sale [Member]
Available-for-sale securities disclosure Items [Abstract]
Available-for-sale securities, Amortized Cost Basis	11,073,810	11,019,116
Available-for-sale securities, Gross Unrealized Gains	234,823	224,456
Available-for-sale securities, Gross Unrealized Losses	7,730	12,468
Available-for-sale securities, Fair Value	11,300,903	11,231,104
Ginnie Mae [Member] | Agency Securities Classified as Available-for-sale [Member]
Available-for-sale securities disclosure Items [Abstract]
Available-for-sale securities, Amortized Cost Basis	2,202,515	2,220,035
Available-for-sale securities, Gross Unrealized Gains	19,486	18,384
Available-for-sale securities, Gross Unrealized Losses	4,438	4,924
Available-for-sale securities, Fair Value	$ 2,217,563	$ 2,233,495