Commitments and Contingent Liabilities - Maximum obligation to extend credit (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Fixed Rate, Commitments to make loans	$ 409,813	$ 55,013
Fixed Rate, Unused lines of credit	74,364	7,625
Fixed Rate, Total	484,177	62,638
Variable Rate, Commitments to make loans	292,290	123,798
Variable Rate, Unused lines of credit	844,106	425,484
Variable Rate, Standby letters of credit	22,250	14,215
Variable Rate, Total	$ 1,158,646	$ 563,497