Commitments and Contingencies - Contractual Amounts (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Contractual amount of off-balance-sheet financial instruments
Total contractual amount of off-balance-sheet financial instruments	$ 363,318	$ 351,968
Commitments to extend credit
Contractual amount of off-balance-sheet financial instruments
Total contractual amount of off-balance-sheet financial instruments	236,653	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	5,966	1,759
Standby letters of credit
Contractual amount of off-balance-sheet financial instruments
Total contractual amount of off-balance-sheet financial instruments	$ 120,699	$ 82,895