Loan and Lease Receivables, Impaired Loans and Leases and Allowance for Loan and Lease Losses (Narrative Disclosures) (Details)	3 Months Ended
	Mar. 31, 2019 USD ($) loans	Mar. 31, 2018 USD ($) loans	Dec. 31, 2018 USD ($)
Financing Receivable, Recorded Investment
SBA loans in the participation sold portfolio, considered impaired	$ 14,700,000		$ 13,200,000
Guaranteed portion of SBA loans sold to third parties	2,300,000	$ 3,100,000
Total amount of outstanding SBA loans sold	81,400,000		83,300,000
Loans and leases transferred to third parties total principal amount	6,800,000	19,700,000
Gain (Loss) Recognized on Participation Interest in Originated Loans	0	$ 0
Total amount of outstanding loans transferred to third parties as loan participations	130,900,000		129,700,000
Total amount of loan participations remaining on the Corporations balance sheet	212,800,000		208,900,000
Loans in the participation sold portfolio, considered impaired	0		0
Loan participations purchased on the Corporation's balance sheet	550,000		569,000
Total gross loans and leases receivable	1,657,646,000		1,619,057,000
Non-accrual troubled debt restructurings	9,600,000		7,600,000
Unfunded commitments, troubled debt restructurings	$ 0
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Loans and leases receivable, difference between recorded investment and unpaid principal balance	$ 7,000,000		7,100,000
Performing troubled debt restructurings	169,000		180,000
Consumer and other:
Financing Receivable, Recorded Investment
Total gross loans and leases receivable	31,744,000		29,227,000
Commercial and industrial
Financing Receivable, Recorded Investment
Total gross loans and leases receivable	$ 466,277,000		$ 462,321,000