TWO Quarterly report pursuant to Section 13 or 15(d)

Available-for-sale Securities Classified by Rate Type (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Adjustable Rate	$ 2,635,890	$ 3,409,699
Available-for-sale Securities, Fixed Rate	10,062,018	8,847,028
Available-for-sale securities, at fair value	12,697,908	12,256,727
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Adjustable Rate	132,157	1,006,621
Available-for-sale Securities, Fixed Rate	9,566,255	8,490,788
Available-for-sale securities, at fair value	9,698,412	9,497,409
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Adjustable Rate	2,503,733	2,403,078
Available-for-sale Securities, Fixed Rate	495,763	356,240
Available-for-sale securities, at fair value	$ 2,999,496	$ 2,759,318