Offsetting Assets and Liabilities Offsetting Assets (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Offsetting Assets [Line Items]
Derivative Instruments Not Designated as Hedging Instruments, Asset, at Fair Value	$ 14,860	$ 0
Derivative Asset, Fair Value, Gross Asset		0
Derivative Asset, Fair Value, Gross Liability	0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral	14,860	0
Derivative, Collateral, Obligation to Return Securities	(2,602)	0
Derivative, Collateral, Obligation to Return Cash	(10,631)	0
Derivative Asset, Fair Value, Amount Offset Against Collateral	$ 1,627	$ 0