Disclosures about Fair Value of Assets and Liabilities - Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Carrying Value
Financial assets:
Cash and cash equivalents	$ 566,810	$ 445,701
Securities purchased under agreements to resell	7,080	5,392
FHLB stock	7,539	7,539
Loans held for sale	798,058	764,503
Loans, net	1,201,695	935,546
Interest receivable	7,196	5,368
Financial liabilities:
Deposits	2,901,464	2,428,621
Line of credit	25,000	25,000
Short-term subordinated debt	30,000	30,000
FHLB advances	1,624	2,006
Interest payable	2,364	1,791
Fair Value
Financial assets:
Cash and cash equivalents	566,810	445,701
Securities purchased under agreements to resell	7,080	5,392
FHLB stock	7,539	7,539
Loans held for sale	798,058	764,503
Loans, net	1,204,002	935,287
Interest receivable	7,196	5,368
Financial liabilities:
Deposits	2,901,331	2,428,478
Line of credit	25,000	25,000
Short-term subordinated debt	30,000	30,000
FHLB advances	1,645	2,031
Interest payable	2,364	1,791
Level 1 | Fair Value
Financial assets:
Cash and cash equivalents	566,810	445,701
Financial liabilities:
Deposits	2,511,551	2,262,378
Level 2 | Fair Value
Financial assets:
Securities purchased under agreements to resell	7,080	5,392
FHLB stock	7,539	7,539
Loans held for sale	798,058	764,503
Interest receivable	7,196	5,368
Financial liabilities:
Deposits	389,780	166,100
Line of credit	25,000	25,000
Short-term subordinated debt	30,000	30,000
FHLB advances	1,645	2,031
Interest payable	2,364	1,791
Level 3 | Fair Value
Financial assets:
Loans, net	$ 1,204,002	$ 935,287