Derivative Financial Instruments Credit Derivative Narrative (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($) contract Rate	Dec. 31, 2014 USD ($)
Credit Default Swap Indices (CDX)
Derivative [Line Items]
Derivative, Number of Instruments Held | contract	4
Derivative, Notional Amount	$ 595,785
Derivative sold protection amount	297,612
Credit Derivative, Purchased Credit Protection	$ 298,173
Derivative, percent cash collateral required | Rate	2.25%
Collateral Already Posted, Aggregate Fair Value	$ 6,750
Credit Default Swap (CDS) [Member]
Derivative [Line Items]
Derivative, Number of Instruments Held | contract	1
Derivative, Notional Amount	$ 2,397	$ 2,652