Loans and Leases - Non-performing Loans and Leases (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	$ 9,448	$ 8,579
Purchased credit impaired became non-performing subsequent to acquisition	87	167
Originated
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	5,034	3,745
Acquired
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	4,414	4,834
Commercial mortgage
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	1,011	872
Commercial mortgage | Originated
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	0	90
Commercial mortgage | Acquired
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	1,011	782
Home equity loans and lines
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	2,323	1,481
Home equity loans and lines | Originated
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	1,833	1,221
Home equity loans and lines | Acquired
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	490	260
Residential mortgage
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	2,647	4,417
Residential mortgage | Originated
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	1,615	1,505
Residential mortgage | Acquired
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	1,032	2,912
Commercial and industrial
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	1,585	1,706
Commercial and industrial | Originated
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	1,011	826
Commercial and industrial | Acquired
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	574	880
Leases
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	1,882	103
Leases | Originated
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	575	103
Leases | Acquired
Loans and Leases Receivable Disclosure [Line Items]
Non-accrual loans and leases	$ 1,307	$ 0