TWO Annual report pursuant to Section 13 and 15(d)

Derivative Instruments and Hedging Activities Schedule of Average Notional Amounts of Derivative Positions (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Inverse Interest-Only Securities [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	$ 885,734	$ 176,064
Derivative Liability, Notional Amount	0	0
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	0	0
Derivative Liability, Notional Amount	3,667,493	377,400
Credit Default Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	250,894	16,101
Derivative Liability, Notional Amount	135,952	0
Interest Rate Swaption [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	1,619,452	6,861
Derivative Liability, Notional Amount	0	0
Other Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	313,630	75,609
Derivative Liability, Notional Amount	726,781	91,745
Forward Sale Commitment [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	128	0
Derivative Liability, Notional Amount	$ 0	$ 0