Loans and the Allowance for Loan Losses (Details) - Loans held-for-sale - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Loans and the Allowance for Loan and Lease Losses (Details) - Purchase credit impaired loans [Line Items]
Total carrying amount	$ 24,845	$ 78,005
Commercial Portfolio Segment [Member]
Loans and the Allowance for Loan and Lease Losses (Details) - Purchase credit impaired loans [Line Items]
Total carrying amount		70,105
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	24,475	7,712
Residential Portfolio Segment [Member]
Loans and the Allowance for Loan and Lease Losses (Details) - Purchase credit impaired loans [Line Items]
Total carrying amount	$ 370	$ 188