Loans and Allowance for Loan Losses - Summary of Changes in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	$ 14,705	$ 12,454	$ 13,721	$ 11,634
Charged-off loans			(251)	(12,369)
Recoveries	32	1,863	420	1,957
Provision for loan losses	481	(195)	1,328	12,900
Ending Balance	15,218	14,122	15,218	14,122
Commercial real estate
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	3,551	3,533	3,324	2,655
Recoveries	6	3	16	4
Provision for loan losses	(412)	(242)	(195)	635
Ending Balance	3,145	3,294	3,145	3,294
Consumer real estate
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,057	1,081	1,063	1,013
Recoveries	1		4
Provision for loan losses	(75)	(97)	(84)	(29)
Ending Balance	983	984	983	984
Construction and land development
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	1,764	911	1,628	1,574
Provision for loan losses	449	576	585	(87)
Ending Balance	2,213	1,487	2,213	1,487
Commercial and industrial
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	7,779	6,395	7,209	5,618
Charged-off loans			(226)	(12,369)
Recoveries	22	1,860	348	1,862
Provision for loan losses	767	(306)	1,237	12,838
Ending Balance	8,568	7,949	8,568	7,949
Consumer
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	120	57	91	76
Charged-off loans			(25)
Recoveries	3		52	91
Provision for loan losses	(30)	22	(25)	(88)
Ending Balance	93	79	93	79
Other
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning Balance	434	477	406	698
Provision for loan losses	(218)	(148)	(190)	(369)
Ending Balance	$ 216	$ 329	$ 216	$ 329

Amount of recovery of loans and lease receivables which had previously been fully or partially written-off as bad debts.

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Amount of loans and leases that have been written off from both loan receivables and allowance reserve for credit loss.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount of expense related to estimated loss from loan and lease transactions.

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