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

Derivative Instruments and Hedging Activities Put and Call Options for TBAs (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Derivative, Notional Amount	$ (33,709,043)invest_DerivativeNotionalAmount	$ (48,115,523)invest_DerivativeNotionalAmount	$ (43,576,146)invest_DerivativeNotionalAmount	$ (37,366,610)invest_DerivativeNotionalAmount
Options Held [Member]
Derivative [Line Items]
Derivative, Notional Amount	(2,500,000)	(2,000,000)	(1,500,000)	0
Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Derivative, Notional Amount	(16,905,295)	(16,200,000)
Derivative, Fair Value, Net	(155,149)	(90,233)
Derivative Financial Instruments, Liabilities [Member] \| Options Held [Member]
Derivative [Line Items]
Derivative, Notional Amount	(2,500,000)	0
Derivative, Cost	(10,843)
Derivative, Fair Value, Net	(5,776)	0
Derivative Financial Instruments, Assets [Member]
Derivative [Line Items]
Derivative, Notional Amount	(26,795,748)	(36,315,523)
Derivative, Fair Value, Net	362,646	380,791
Derivative Financial Instruments, Assets [Member] \| Options Held [Member]
Derivative [Line Items]
Derivative, Notional Amount	0	(2,000,000)
Derivative, Cost		(605)
Derivative, Fair Value, Net	$ 0	$ 90