Fair Value Measurements - Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair value of financial assets
Securities - held-to-maturity	$ 139,377	$ 140,315
FHLB and FRB stock	52,262	50,498
Financial Liabilities:
Time deposits	637,295	748,250
Securities sold under agreements to repurchase	81,842	75,177
Other borrowings	1,076,075	1,071,742
Trust preferred debentures	16,863	16,691
(Level 1)
Fair value of financial assets
Cash and cash equivalents	80,389	84,303
Securities - held-to-maturity	0	0
FHLB and FRB stock	0	0
Accrued interest receivable	0	0
Loans and leases, net	0	0
Financial Liabilities:
Time deposits	0	0
Other deposits	0	0
Securities sold under agreements to repurchase	0	0
Other borrowings	0	0
Trust preferred debentures	0	0
Accrued interest payable	0	0
(Level 2)
Fair value of financial assets
Cash and cash equivalents	0	0
Securities - held-to-maturity	139,377	140,315
FHLB and FRB stock	52,262	50,498
Accrued interest receivable	20,922	20,122
Loans and leases, net	6,500	4,617
Financial Liabilities:
Time deposits	631,489	744,310
Other deposits	4,251,664	4,089,557
Securities sold under agreements to repurchase	81,842	75,177
Other borrowings	1,074,081	1,069,609
Trust preferred debentures	21,921	22,012
Accrued interest payable	2,408	2,054
(Level 3)
Fair value of financial assets
Cash and cash equivalents	0	0
Securities - held-to-maturity	0	0
FHLB and FRB stock	0	0
Accrued interest receivable	0	0
Loans and leases, net	4,642,808	4,551,103
Financial Liabilities:
Time deposits	0	0
Other deposits	0	0
Securities sold under agreements to repurchase	0	0
Other borrowings	0	0
Trust preferred debentures	0	0
Accrued interest payable	0	0
Carrying Amount
Fair value of financial assets
Cash and cash equivalents	80,389	84,303
Securities - held-to-maturity	140,579	139,216
FHLB and FRB stock	52,262	50,498
Accrued interest receivable	20,922	20,122
Loans and leases, net	4,790,529	4,632,288
Financial Liabilities:
Time deposits	637,295	748,250
Other deposits	4,251,664	4,089,557
Securities sold under agreements to repurchase	81,842	75,177
Other borrowings	1,076,075	1,071,742
Trust preferred debentures	16,863	16,691
Accrued interest payable	2,408	2,054
Fair Value
Fair value of financial assets
Cash and cash equivalents	80,389	84,303
Securities - held-to-maturity	139,377	140,315
FHLB and FRB stock	52,262	50,498
Accrued interest receivable	20,922	20,122
Loans and leases, net	4,649,308	4,555,720
Financial Liabilities:
Time deposits	631,489	744,310
Other deposits	4,251,664	4,089,557
Securities sold under agreements to repurchase	81,842	75,177
Other borrowings	1,074,081	1,069,609
Trust preferred debentures	21,921	22,012
Accrued interest payable	$ 2,408	$ 2,054