Commitments, Contingencies, and Concentrations of Credit Risk - Schedule of Outstanding Loan Commitments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Loan commitments	$ 332,963	$ 386,944
Unused lines of credit	1,088,060	935,728
Total	1,421,023	1,322,672
Fixed Rate
Loss Contingencies [Line Items]
Loan commitments	238,745	263,775
Unused lines of credit	188,014	169,278
Total	426,759	433,053
Variable Rate
Loss Contingencies [Line Items]
Loan commitments	94,218	123,169
Unused lines of credit	900,046	766,450
Total	$ 994,264	$ 889,619