Loans - Nonperforming Loans (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Summary of nonperforming loans
Total accruing loans contractually past due 90 days or more as to interest or principal payments	$ 3,692	$ 1,283
Commercial
Summary of nonperforming loans
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,823	11
Commercial real estate
Summary of nonperforming loans
Total accruing loans contractually past due 90 days or more as to interest or principal payments	700	277
Home equity
Summary of nonperforming loans
Total accruing loans contractually past due 90 days or more as to interest or principal payments	1,169	995
Nonperforming
Summary of nonperforming loans
Total nonaccrual loans	47,841	44,334
Other real estate owned and repossessed assets	16,395	17,187
Total nonperforming assets	64,236	61,521
Nonperforming | Commercial
Summary of nonperforming loans
Total nonaccrual loans	16,717	13,178
Nonperforming | Commercial real estate
Summary of nonperforming loans
Total nonaccrual loans	20,828	19,877
Nonperforming | Real estate construction and land development
Summary of nonperforming loans
Total nonaccrual loans	79	80
Nonperforming | Residential mortgage
Summary of nonperforming loans
Total nonaccrual loans	6,749	6,969
Nonperforming | Consumer installment
Summary of nonperforming loans
Total nonaccrual loans	755	879
Nonperforming | Home equity
Summary of nonperforming loans
Total nonaccrual loans	$ 2,713	$ 3,351