DISCLOSURES REGARDING FAIR VALUES OF FINANCIAL INSTRUMENTS - Fair Value and Related Disclosures for Debt Securities (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 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	$ 3,754	$ 4,376
Held-to-maturities, Gains	128	211
Held-to-maturities, Losses	0	0
Held-to-maturities, Fair Value	3,882	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	10,711,999	11,019,116
Available-for-sale securities, Gross Unrealized Gains	242,301	224,456
Available-for-sale securities, Gross Unrealized Losses	5,517	12,468
Available-for-sale securities, Fair Value	10,948,783	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	2,753,329	2,220,035
Available-for-sale securities, Gross Unrealized Gains	16,838	18,384
Available-for-sale securities, Gross Unrealized Losses	5,709	4,924
Available-for-sale securities, Fair Value	$ 2,764,458	$ 2,233,495