Annual report pursuant to Section 13 and 15(d)

Derivative Instruments and Hedging Activities Schedule of Interest Rate Swaptions (Details)

v2.4.0.8
Derivative Instruments and Hedging Activities Schedule of Interest Rate Swaptions (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Interest Rate Swaption [Member] | Long [Member] | Variable Income Interest Rate [Member]
   
Derivative [Line Items]    
Derivative, Cost $ 233,935 $ 133,908
Derivative Asset, Fair Value, Net 363,566 102,048
Derivative, Weighted Average Remaining Maturity 38.162 53.376
Interest Rate Swaption [Member] | Long [Member] | Variable Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Cost 10,431 3,983
Derivative Asset, Fair Value, Net 10,458 30
Derivative, Weighted Average Remaining Maturity 2.776 5.375
Interest Rate Swaption [Member] | Long [Member] | Variable Income Interest Rate [Member] | Six Months or Longer Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Cost 223,504 129,925
Derivative Asset, Fair Value, Net 353,108 102,018
Derivative, Weighted Average Remaining Maturity 39.144 53.383
Interest Rate Swaption [Member] | Long [Member] | Fixed Income Interest Rate [Member]
   
Derivative [Line Items]    
Derivative, Cost 3,991  
Derivative Asset, Fair Value, Net 681  
Derivative, Weighted Average Remaining Maturity 1.933  
Interest Rate Swaption [Member] | Long [Member] | Fixed Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Cost 3,991  
Derivative Asset, Fair Value, Net 681  
Derivative, Weighted Average Remaining Maturity 1.933  
Interest Rate Swaption [Member] | Short [Member] | Variable Income Interest Rate [Member]
   
Derivative [Line Items]    
Derivative, Cost (84,703)  
Derivative Asset, Fair Value, Net (94,040)  
Derivative, Weighted Average Remaining Maturity 33.679  
Interest Rate Swaption [Member] | Short [Member] | Variable Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Cost (3,455)  
Derivative Asset, Fair Value, Net (7,679)  
Derivative, Weighted Average Remaining Maturity 1.933  
Interest Rate Swaption [Member] | Short [Member] | Variable Income Interest Rate [Member] | Six Months or Longer Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Cost (81,248)  
Derivative Asset, Fair Value, Net (86,361)  
Derivative, Weighted Average Remaining Maturity 42.023  
Interest Rate Swaption [Member] | Short [Member] | Fixed Income Interest Rate [Member]
   
Derivative [Line Items]    
Derivative, Cost (3,455)  
Derivative Asset, Fair Value, Net (462)  
Derivative, Weighted Average Remaining Maturity 1.933  
Interest Rate Swaption [Member] | Short [Member] | Fixed Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Cost (3,455)  
Derivative Asset, Fair Value, Net (462)  
Derivative, Weighted Average Remaining Maturity 1.933  
Underlying Swap [Member] | Long [Member] | Variable Income Interest Rate [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount 6,675,000 4,950,000
Derivative, Average Fixed Interest Rate 4.178% 3.753%
Derivative, Description of Variable Rate Basis 3M Libor 3M Libor
Derivative, Weighted Average Remaining Maturity 9.101 9.758
Underlying Swap [Member] | Long [Member] | Variable Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount 675,000 300,000
Derivative, Average Fixed Interest Rate 3.326% 4.00%
Derivative, Description of Variable Rate Basis 3M Libor 3M Libor
Derivative, Weighted Average Remaining Maturity 10 10
Underlying Swap [Member] | Long [Member] | Variable Income Interest Rate [Member] | Six Months or Longer Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount 6,000,000 4,650,000
Derivative, Average Fixed Interest Rate 4.274% 3.737%
Derivative, Description of Variable Rate Basis 3M Libor 3M Libor
Derivative, Weighted Average Remaining Maturity 9 9.742
Underlying Swap [Member] | Long [Member] | Fixed Income Interest Rate [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount 275,000  
Derivative, Average Fixed Interest Rate 2.89%  
Derivative, Description of Variable Rate Basis 3M Libor  
Derivative, Weighted Average Remaining Maturity 10  
Underlying Swap [Member] | Long [Member] | Fixed Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount 275,000  
Derivative, Average Fixed Interest Rate 2.89%  
Derivative, Description of Variable Rate Basis 3M Libor  
Derivative, Weighted Average Remaining Maturity 10  
Underlying Swap [Member] | Short [Member] | Variable Income Interest Rate [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount (1,310,000)  
Derivative, Average Fixed Interest Rate 2.722%  
Derivative, Description of Variable Rate Basis 3M Libor  
Derivative, Weighted Average Remaining Maturity 8.053  
Underlying Swap [Member] | Short [Member] | Variable Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount (510,000)  
Derivative, Average Fixed Interest Rate 1.60%  
Derivative, Description of Variable Rate Basis 3M Libor  
Derivative, Weighted Average Remaining Maturity 5  
Underlying Swap [Member] | Short [Member] | Variable Income Interest Rate [Member] | Six Months or Longer Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount (800,000)  
Derivative, Average Fixed Interest Rate 3.438%  
Derivative, Description of Variable Rate Basis 3M Libor  
Derivative, Weighted Average Remaining Maturity 10  
Underlying Swap [Member] | Short [Member] | Fixed Income Interest Rate [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount (510,000)  
Derivative, Average Fixed Interest Rate 1.60%  
Derivative, Description of Variable Rate Basis 3M Libor  
Derivative, Weighted Average Remaining Maturity 5  
Underlying Swap [Member] | Short [Member] | Fixed Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]
   
Derivative [Line Items]    
Derivative, Notional Amount $ (510,000)  
Derivative, Average Fixed Interest Rate 1.60%  
Derivative, Description of Variable Rate Basis 3M Libor  
Derivative, Weighted Average Remaining Maturity 5