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

Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Schedule of Average Notional Amounts of Derivative Positions (Details)

Derivative Instruments and Hedging Activities Schedule of Average Notional Amounts of Derivative Positions (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012
Inverse Interest-Only Securities [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	$ 1,953,128	$ 1,669,944
Derivative Liability, Average Notional Amount	0	0
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	0	0
Derivative Liability, Average Notional Amount	11,327,391	8,625,967
Credit Default Swap [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	545,611	554,568
Derivative Liability, Average Notional Amount	48,576	91,555
Interest Rate Swaption [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	4,891,304	3,687,328
Derivative Liability, Average Notional Amount	0	0
Other Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	304,348	278,741
Derivative Liability, Average Notional Amount	0	564,416
Short US Treasury Securities [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	0	0
Derivative Liability, Average Notional Amount	46,739	15,693
Forward Purchase Commitment [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	45,872	15,894
Derivative Liability, Average Notional Amount	0	0
Forward Sale Commitment [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Notional Amount	0	3,199
Derivative Liability, Average Notional Amount	$ 0	$ 0