Loans (Summary of Nonperforming Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Impaired, Interest Income Recognized on Nonaccrual Loans While In Accruing Status	$ 2,100	$ 1,300	$ 400
Summary of nonperforming loans
Total nonaccrual loans	85,433	63,095
Other real estate owned and repossessed assets	6,256	8,807
Total nonperforming assets	91,689	71,902
Commercial
Summary of nonperforming loans
Total nonaccrual loans	30,139
Commercial real estate:
Summary of nonperforming loans
Total nonaccrual loans	42,414	$ 29,545
Real estate construction and land development
Summary of nonperforming loans
Total nonaccrual loans	12
Residential mortgage
Summary of nonperforming loans
Total nonaccrual loans	7,988
Consumer installment
Summary of nonperforming loans
Total nonaccrual loans	1,276
Home equity
Summary of nonperforming loans
Total nonaccrual loans	3,604
Owner-occupied | Commercial
Summary of nonperforming loans
Total nonaccrual loans	16,056
Non-owner occupied | Commercial
Summary of nonperforming loans
Total nonaccrual loans	23,021
Vacant land | Commercial
Summary of nonperforming loans
Total nonaccrual loans	$ 3,337