Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Credit Risk - Counterparty Exposure (Details)

v2.4.1.9
Derivative Instruments and Hedging Activities Credit Risk - Counterparty Exposure (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Credit Derivatives [Line Items]    
Derivative Asset, Fair Value, Gross Asset $ 362,646us-gaap_DerivativeFairValueOfDerivativeAsset $ 380,791us-gaap_DerivativeFairValueOfDerivativeAsset
Derivative Liability, Fair Value, Gross Liability 155,149us-gaap_DerivativeFairValueOfDerivativeLiability 90,233us-gaap_DerivativeFairValueOfDerivativeLiability
Collateral Securities Repledged, Delivered, or Used (104,477)us-gaap_CollateralSecuritiesRepledgedDeliveredOrUsed  
Collateral Already Posted, Aggregate Fair Value $ 336,319us-gaap_CollateralAlreadyPostedAggregateFairValue