Commitments and Contingencies - Contractual Amounts (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Contractual amount of off-balance-sheet financial instruments
Total contractual amount of off-balance-sheet financial instruments	$ 325,890	$ 351,968
Commitments to extend credit
Contractual amount of off-balance-sheet financial instruments
Total contractual amount of off-balance-sheet financial instruments	246,058	267,314
Commitments to originate residential first and second mortgage loans
Contractual amount of off-balance-sheet financial instruments
Total contractual amount of off-balance-sheet financial instruments	9,582	1,759
Standby letters of credit
Contractual amount of off-balance-sheet financial instruments
Total contractual amount of off-balance-sheet financial instruments	$ 70,250	$ 82,895