Disclosures about Fair Value of Assets and Liabilities - Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financial assets:
Loans held for sale	$ 19,592	$ 11,886
Carrying Value
Financial assets:
Cash and cash equivalents	506,709	336,524
Securities purchased under agreements to resell	6,723	6,875
FHLB stock	20,369	7,974
Loans held for sale	2,074,197	820,569
Loans, net	3,012,468	2,045,423
Interest receivable	18,359	13,827
Financial liabilities:
Deposits	5,478,075	3,231,086
Lines of credit	6,540	33,150
Short-term subordinated debt	12,200	10,582
FHLB advances	162,699	151,721
Interest payable	11,938	4,132
Fair Value
Financial assets:
Cash and cash equivalents	506,709	336,524
Securities purchased under agreements to resell	6,723	6,875
FHLB stock	20,369	7,974
Loans held for sale	2,074,197	820,569
Loans, net	2,999,580	2,041,772
Interest receivable	18,359	13,827
Financial liabilities:
Deposits	5,478,682	3,230,397
Lines of credit	6,540	33,150
Short-term subordinated debt	12,200	10,582
FHLB advances	162,803	151,723
Interest payable	11,938	4,132
Level 1 | Fair Value
Financial assets:
Cash and cash equivalents	506,709	336,524
Financial liabilities:
Deposits	3,303,736	2,550,632
Level 2 | Fair Value
Financial assets:
Securities purchased under agreements to resell	6,723	6,875
FHLB stock	20,369	7,974
Loans held for sale	2,074,197	820,569
Interest receivable	18,359	13,827
Financial liabilities:
Deposits	2,174,946	679,765
Lines of credit	6,540	33,150
Short-term subordinated debt	12,200	10,582
FHLB advances	162,803	151,723
Interest payable	11,938	4,132
Level 3 | Fair Value
Financial assets:
Loans, net	$ 2,999,580	$ 2,041,772