Disclosures about Fair Value of Assets and Liabilities - Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Financial assets:
Loans held for sale	$ 18,938	$ 19,592
Carrying Value
Financial assets:
Cash and cash equivalents	568,082	506,709
Securities purchased under agreements to resell	6,685	6,723
FHLB stock	46,156	20,369
Loans held for sale	2,777,070	2,074,197
Loans, net	3,501,770	3,012,468
Interest receivable	18,139	18,359
Financial liabilities:
Deposits	6,722,705	5,478,075
Lines of credit		6,540
Short-term subordinated debt	12,650	12,200
FHLB advances	431,917	162,699
Interest payable	10,219	11,938
Fair Value
Financial assets:
Cash and cash equivalents	568,082	506,709
Securities purchased under agreements to resell	6,685	6,723
FHLB stock	46,156	20,369
Loans held for sale	2,777,070	2,074,197
Loans, net	3,475,393	2,999,580
Interest receivable	18,139	18,359
Financial liabilities:
Deposits	6,730,101	5,478,682
Lines of credit		6,540
Short-term subordinated debt	12,650	12,200
FHLB advances	431,283	162,803
Interest payable	10,219	11,938
Level 1 | Fair Value
Financial assets:
Cash and cash equivalents	568,082	506,709
Financial liabilities:
Deposits	3,967,232	3,303,736
Level 2 | Fair Value
Financial assets:
Securities purchased under agreements to resell	6,685	6,723
FHLB stock	46,156	20,369
Loans held for sale	2,777,070	2,074,197
Interest receivable	18,139	18,359
Financial liabilities:
Deposits	2,762,869	2,174,946
Lines of credit		6,540
Short-term subordinated debt	12,650	12,200
FHLB advances	431,283	162,803
Interest payable	10,219	11,938
Level 3 | Fair Value
Financial assets:
Loans, net	$ 3,475,393	$ 2,999,580