Loans and Allowance for Credit Losses Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for Loan and Lease Losses	$ 2,200	$ 3,500	$ (1,500)	$ 6,000
Allowance for Loan and Lease Losses, Period Increase (Decrease)			$ 7,500
Impaired loans with principal balances approximately in percentage			72.00%	79.00%
Loan to value ratio in the Corporation's policy	70.00%		70.00%
Recorded investment, with no related allowance	$ 59,992		$ 59,992		$ 59,073
TDR additional commitments to lend	6,000		6,000		$ 3,900
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum balance of loans evaluated individually for impairment			1,000
Minimum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum balance of loans evaluated individually for impairment			1,000
Impaired loans balances, real estate as collateral	$ 1,000		$ 1,000