Fair Value Disclosures - Assets, Liabilities and Off-balance Sheet Items Not Measured at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Assets:
Held-to-maturity securities	$ 175,296	$ 141,575
Other real estate owned	540	1,200
Total assets	1,725		$ 1,847
Deposits:
Time deposits	709,437	670,077
Subordinated notes	94,696	94,574
Fair Value [Member]
Assets:
Cash and short-term interest-earning assets	84,567	109,420
Held-to-maturity securities	175,296	141,575
Loans held for sale	1,531	1,798
Net loans and leases held for investment	4,121,087	3,924,329
Servicing rights	8,911	11,496
Total assets	4,391,392	4,188,618
Deposits:
Demand and savings deposits, non-maturity	3,412,673	3,215,856
Time deposits	712,030	664,738
Total deposits	4,124,703	3,880,594
Short-term borrowings	39,350	189,768
Long-term debt	171,177	144,021
Subordinated notes	96,572	95,113
Total liabilities	4,431,802	4,309,496
Off-Balance-Sheet:
Commitments to extend credit	(8,066)	(2,516)
Fair Value [Member] | Level 1 [Member]
Assets:
Cash and short-term interest-earning assets	84,567	109,420
Held-to-maturity securities	0	0
Loans held for sale	0	0
Net loans and leases held for investment	0	0
Servicing rights	0	0
Total assets	84,567	109,420
Deposits:
Demand and savings deposits, non-maturity	3,412,673	3,215,856
Time deposits	0	0
Total deposits	3,412,673	3,215,856
Short-term borrowings	0	0
Long-term debt	0	0
Subordinated notes	0	0
Total liabilities	3,412,673	3,215,856
Off-Balance-Sheet:
Commitments to extend credit	0	0
Fair Value [Member] | Level 2 [Member]
Assets:
Cash and short-term interest-earning assets	0	0
Held-to-maturity securities	175,296	141,575
Loans held for sale	1,531	1,798
Net loans and leases held for investment	0	0
Servicing rights	0	0
Total assets	176,827	143,373
Deposits:
Demand and savings deposits, non-maturity	0	0
Time deposits	712,030	664,738
Total deposits	712,030	664,738
Short-term borrowings	39,350	189,768
Long-term debt	171,177	144,021
Subordinated notes	96,572	95,113
Total liabilities	1,019,129	1,093,640
Off-Balance-Sheet:
Commitments to extend credit	(8,066)	(2,516)
Fair Value [Member] | Level 3 [Member]
Assets:
Cash and short-term interest-earning assets	0	0
Held-to-maturity securities	0	0
Loans held for sale	0	0
Net loans and leases held for investment	4,121,087	3,924,329
Servicing rights	8,911	11,496
Total assets	4,129,998	3,935,825
Deposits:
Demand and savings deposits, non-maturity	0	0
Time deposits	0	0
Total deposits	0	0
Short-term borrowings	0	0
Long-term debt	0	0
Subordinated notes	0	0
Total liabilities	0	0
Off-Balance-Sheet:
Commitments to extend credit	0	0
Carrying Amount [Member]
Assets:
Cash and short-term interest-earning assets	84,567	109,420
Held-to-maturity securities	172,946	142,634
Federal Home Loan Bank, Federal Reserve Bank and other stock	32,755	28,337
Loans held for sale	1,498	1,754
Net loans and leases held for investment	4,110,916	3,950,265
Servicing rights	6,599	6,768
Total assets	4,409,281	4,239,178
Deposits:
Demand and savings deposits, non-maturity	3,412,673	3,215,856
Time deposits	709,437	670,077
Total deposits	4,122,110	3,885,933
Short-term borrowings	39,350	189,768
Long-term debt	170,195	145,330
Subordinated notes	94,696	94,574
Total liabilities	4,426,351	4,315,605
Off-Balance-Sheet:
Commitments to extend credit	0	0
Fair Value Measured on Recurring Basis [Member]
Assets:
Net loans and leases held for investment	1,725	1,779
Total assets	298,410	333,130
Deposits:
Total liabilities	861	501
Fair Value Measured on Recurring Basis [Member] | Level 1 [Member]
Assets:
Net loans and leases held for investment	0	0
Total assets	2,865	2,165
Deposits:
Total liabilities	0	0
Fair Value Measured on Recurring Basis [Member] | Level 2 [Member]
Assets:
Net loans and leases held for investment	0	0
Total assets	266,895	303,457
Deposits:
Total liabilities	490	170
Fair Value Measured on Recurring Basis [Member] | Level 3 [Member]
Assets:
Net loans and leases held for investment	1,725	1,779
Total assets	28,650	27,508
Deposits:
Total liabilities	$ 371	$ 331