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	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Adjustable Rate	$ 3,061,731	$ 3,409,699
Available-for-sale Securities, Fixed Rate	10,046,520	8,847,028
Available-for-sale securities, at fair value	13,108,251	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	548,509	1,006,621
Available-for-sale Securities, Fixed Rate	9,503,019	8,490,788
Available-for-sale securities, at fair value	10,051,528	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	2,513,222	2,403,078
Available-for-sale Securities, Fixed Rate	543,501	356,240
Available-for-sale securities, at fair value	$ 3,056,723	$ 2,759,318