DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS - Fair Value and Related Disclosures for Debt Securities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Residential Mortgage Securities Classified as held-to-Maturity [Member]
Held-to-maturity securities disclosure [Abstract]
Held-to-maturities, Amortized Cost Basis	$ 4,376	$ 5,989
Held-to-maturities, Gains	211	309
Held-to-maturities, Losses	0	0
Held-to-maturities, Fair Value	4,587	6,298
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	11,019,116	11,904,660
Available-for-sale securities, Gross Unrealized Gains	224,456	296,114
Available-for-sale securities, Gross Unrealized Losses	12,468	1,787
Available-for-sale securities, Fair Value	11,231,104	12,198,987
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	2,220,035	1,614,997
Available-for-sale securities, Gross Unrealized Gains	18,384	32,298
Available-for-sale securities, Gross Unrealized Losses	4,924	176
Available-for-sale securities, Fair Value	$ 2,233,495	$ 1,647,119