Fair Value Measurement - Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Carrying Amount
Financial assets:
Cash and cash equivalents	$ 114,824	$ 120,719
Investment securities:
Held to maturity, at carrying value	2,895	3,083
Mortgage-backed securities:
Held to maturity, at carrying value	138,060	159,848
Federal Home Loan Bank stock, at cost	45,039	32,583
Equity investments	6,395	6,302
Loans, net of allowance for loan losses	3,474,788	3,285,780
Loans held for sale	1,000	601
Financial liabilities:
Deposits	4,490,767	4,425,030
Other borrowings	9,626	36,810
Federal Home Loan Bank borrowings	978,951	719,065
Subordinated notes, net of unamortized debt issuance costs	98,532	98,407
Trust preferred subordinated debentures, net of unamortized debt issuance costs	60,249	60,246
Estimated Fair Value
Financial assets:
Cash and cash equivalents	114,824	120,719
Investment securities:
Held to maturity, at carrying value	2,928	3,046
Mortgage-backed securities:
Held to maturity, at carrying value	144,112	156,735
Federal Home Loan Bank stock, at cost	45,039	32,583
Equity investments	6,395	6,302
Loans, net of allowance for loan losses	3,560,407	3,251,923
Loans held for sale	1,000	601
Financial liabilities:
Deposits	4,491,593	4,417,902
Other borrowings	9,626	36,810
Federal Home Loan Bank borrowings	983,894	708,904
Subordinated notes, net of unamortized debt issuance costs	98,655	97,611
Trust preferred subordinated debentures, net of unamortized debt issuance costs	59,525	54,729
Estimated Fair Value | Level 1
Financial assets:
Cash and cash equivalents	114,824	120,719
Investment securities:
Held to maturity, at carrying value	0	0
Mortgage-backed securities:
Held to maturity, at carrying value	0	0
Federal Home Loan Bank stock, at cost	0	0
Equity investments	0	0
Loans, net of allowance for loan losses	0	0
Loans held for sale	0	0
Financial liabilities:
Deposits	0	0
Other borrowings	0	0
Federal Home Loan Bank borrowings	0	0
Subordinated notes, net of unamortized debt issuance costs	0	0
Trust preferred subordinated debentures, net of unamortized debt issuance costs	0	0
Estimated Fair Value | Level 2
Financial assets:
Cash and cash equivalents	0	0
Investment securities:
Held to maturity, at carrying value	2,928	3,046
Mortgage-backed securities:
Held to maturity, at carrying value	144,112	156,735
Federal Home Loan Bank stock, at cost	45,039	32,583
Equity investments	6,395	6,302
Loans, net of allowance for loan losses	0	0
Loans held for sale	1,000	601
Financial liabilities:
Deposits	4,491,593	4,417,902
Other borrowings	9,626	36,810
Federal Home Loan Bank borrowings	983,894	708,904
Subordinated notes, net of unamortized debt issuance costs	98,655	97,611
Trust preferred subordinated debentures, net of unamortized debt issuance costs	59,525	54,729
Estimated Fair Value | Level 3
Financial assets:
Cash and cash equivalents	0	0
Investment securities:
Held to maturity, at carrying value	0	0
Mortgage-backed securities:
Held to maturity, at carrying value	0	0
Federal Home Loan Bank stock, at cost	0	0
Equity investments	0	0
Loans, net of allowance for loan losses	3,560,407	3,251,923
Loans held for sale	0	0
Financial liabilities:
Deposits	0	0
Other borrowings	0	0
Federal Home Loan Bank borrowings	0	0
Subordinated notes, net of unamortized debt issuance costs	0	0
Trust preferred subordinated debentures, net of unamortized debt issuance costs	$ 0	$ 0