Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details)

v2.4.0.6
Derivative Instruments and Hedging Activities Interest Rate Sensitive Assets/Liabilities (Details) (USD $)
Jun. 30, 2012
Dec. 31, 2011
Derivatives, Fair Value [Line Items]    
Available-for-sale Securities, Interest-only $ 61,200,000 $ 48,400,000
Agency To-be-Announced Securities, Notional Amount, Long   275,000,000
Agency To-be-Announced Securities, Notional Amount, Short   850,000,000
Agency To-be-Announced Securities, Fair Value, Asset   2,700,000
Agency To-be-Announced Securities, Fair Value, Liability   (5,700,000)
Trading Securities 999,375,000 1,003,301,000
Derivative Asset, Fair Value, Gross Asset 361,073,000 251,856,000
Derivative Liability, Fair Value, Gross Liability 82,619,000 49,080,000
Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net 361,073,000 251,856,000
Derivative Asset, Notional Amount 6,563,915,000 4,855,985,000
Forward Purchase Commitment [Member] | Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net 0 0
Derivative Asset, Notional Amount 32,406,000 0
Forward Sale Commitment [Member] | Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net   0
Derivative Asset, Notional Amount   $ 5,202,000