Derivative Financial Instruments Offsetting of Derivative Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Offsetting of Derivative Assets and Liabilities [Abstract]
Derivative Asset, Fair Value, Gross Asset	$ 585,474	$ 592,208
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	(398)	(70)
Derivative Asset, Fair Value, Amount Offset Against Collateral	585,076	592,138
Derivative Liability, Fair Value, Gross Liability	(398)	(70)
Derivative Liability, Fair Value, Amount Not Offset Against Collateral	398	70
Derivative Liability, Fair Value, Amount Offset Against Collateral	$ 0	$ 0

Fair value, after offset of derivative liability, of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References+ Details

Fair value, after offset of derivative asset, of financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References+ Details