Loans and the Allowance for Loan Losses (Details) - Loans held-for-sale - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Loans and the Allowance for Loan and Lease Losses (Details) - Purchase credit impaired loans [Line Items]
Total carrying amount	$ 45,886	$ 24,845
Commercial Real Estate Portfolio Segment [Member]
Loans and the Allowance for Loan and Lease Losses (Details) - Purchase credit impaired loans [Line Items]
Total carrying amount	45,598	24,475
Residential Real Estate Portfolio Segment [Member]
Loans and the Allowance for Loan and Lease Losses (Details) - Purchase credit impaired loans [Line Items]
Total carrying amount	$ 288	$ 370