Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Schedule of Interest Rate Swaps Associated with U.S. Treasuries and Other RMBS (Details)

v2.4.0.6
Derivative Instruments and Hedging Activities Schedule of Interest Rate Swaps Associated with U.S. Treasuries and Other RMBS (Details) (Interest Rate Swaps Associated with U.S. Treasuries and Other RMBS [Member], USD $)
In Thousands, unless otherwise specified
Mar. 31, 2012
Dec. 31, 2011
Derivative [Line Items]    
Derivative, Notional Amount $ 1,000,000 $ 1,250,000
More than One and within Two Years from Balance Sheet Date [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount $ 1,000,000 $ 1,250,000
Derivative, Average Fixed Interest Rate 0.6439% 0.6196%
Derivative, Average Variable Interest Rate 0.51505% 0.3393%
Derivative, Average Remaining Maturity 1.2563 1.535