Allowance for Loan Losses (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Minimum non-performing substandard loans outstanding for allowance for credit losses	$ 300
Minimum non-performing substandard doubtful loans outstanding for allowance for credit losses	100
Allowance for credit losses, write-downs	6,500	$ 14,700
Impaired financing receivable, interest income, cash basis method	600	900	$ 1,300
Loans and leases receivable, impaired, interest lost on nonaccrual loans	3,200	2,800	$ 5,500
Loan commitments	6,385,147	6,136,313
Total impaired loans with no related allowance
Financing Receivable, Allowance for Credit Losses [Line Items]
Loan commitments	$ 7,000	$ 200