Loans and Allowance for Credit Losses Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Provision for credit losses	$ 2,511	$ 2,200	$ 4,041	$ (1,500)
Impaired loans with principal balances approximately in percentage			89.00%	72.00%
Loan to value ratio in the Corporation's policy	70.00%		70.00%
Recorded investment, with no related allowance	$ 53,352		$ 53,352		$ 49,953
TDR additional commitments to lend	3,800		3,800		$ 5,300
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
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum balance of loans evaluated individually for impairment			$ 1,000