Loans and Leases - Outstanding Principal Balance and Related Carrying Amounts (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Total Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	$ 3,706	$ 3,652
Carrying amount	3,521	3,438
VIST Financial Corp. (VIST Financial) | Acquired Credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	12,564	12,822
Carrying amount	10,793	11,036
VIST Financial Corp. (VIST Financial) | Acquired Non-Credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	248,091	256,265
Carrying amount	246,104	254,162
VIST Financial Corp. (VIST Financial) | Total Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	260,655	269,087
Carrying amount	$ 256,897	$ 265,198