Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details)

v2.4.0.6
Derivative Instruments and Hedging Activities Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) (USD $)
In Thousands, unless otherwise specified
Sep. 30, 2012
Dec. 31, 2011
Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net $ 496,788 $ 251,856
Derivative Asset, Notional Amount 8,562,259 4,855,985
Derivative Financial Instruments, Liabilities [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Liability, Fair Value, Net (132,322) (49,080)
Derivative Liability, Notional Amount 13,095,000 6,814,812
Inverse Interest-Only Securities [Member] | Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net 332,569 157,421
Derivative Asset, Notional Amount 2,031,621 1,131,084
Inverse Interest-Only Securities [Member] | Derivative Financial Instruments, Liabilities [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Liability, Fair Value, Net 0 0
Derivative Liability, Notional Amount 0 0
Interest Rate Swap [Member] | Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net 0 0
Derivative Asset, Notional Amount 0 0
Interest Rate Swap [Member] | Derivative Financial Instruments, Liabilities [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Liability, Fair Value, Net (132,322) (28,790)
Derivative Liability, Notional Amount 13,095,000 5,810,000
Credit Default Swap [Member] | Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net 54,584 86,136
Derivative Asset, Notional Amount 610,707 544,699
Credit Default Swap [Member] | Derivative Financial Instruments, Liabilities [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Liability, Fair Value, Net 0 (14,638)
Derivative Liability, Notional Amount 0 154,812
Interest Rate Swaption [Member] | Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net 105,064 5,635
Derivative Asset, Notional Amount 5,150,000 2,900,000
Interest Rate Swaption [Member] | Derivative Financial Instruments, Liabilities [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Liability, Fair Value, Net 0 0
Derivative Liability, Notional Amount 0 0
Other Contract [Member] | Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net 3,967 2,664
Derivative Asset, Notional Amount 450,000 275,000
Other Contract [Member] | Derivative Financial Instruments, Liabilities [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Liability, Fair Value, Net 0 (5,652)
Derivative Liability, Notional Amount 0 850,000
Forward Purchase Commitment [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net 604  
Derivative Asset, Notional Amount 319,931  
Forward Purchase Commitment [Member] | Derivative Financial Instruments, Liabilities [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Liability, Fair Value, Net 0  
Derivative Liability, Notional Amount 0  
Forward Sale Commitment [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Notional Amount   5,202
Forward Sale Commitment [Member] | Derivative Financial Instruments, Assets [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Asset, Fair Value, Net   0
Forward Sale Commitment [Member] | Derivative Financial Instruments, Liabilities [Member]
   
Derivatives, Fair Value [Line Items]    
Derivative Liability, Fair Value, Net   0
Derivative Liability, Notional Amount   $ 0