Derivative Instruments Narrative (Details) (USD $)			3 Months Ended	6 Months Ended
	Jun. 30, 2013 Contracts	Dec. 31, 2012	Jun. 30, 2012 Deposit liabilities	Jun. 30, 2012 Deposit liabilities
Derivative [Line Items]
Derivatives Number of Instruments Held	1
Fair Value Hedge Cumulative Reduction To Expense			$ 2,500,000	$ 4,900,000
Collateral posted to counterparty	$ 1,730,000	$ 12,130,000
Deficiency guarantee government backing percent	80.00%