Credit Quality - Schedule of Charged-off Troubled Debt Restructurings on Financing Receivables (Detail) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020 USD ($) Contract	Jun. 30, 2020 USD ($) Contract	Jun. 30, 2019 USD ($) Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	1	1	1
Recorded Investment | $	$ 690	$ 690	$ 1,321
Construction & Land Development [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	1	1	0
Recorded Investment | $	$ 690	$ 690	$ 0
Bankcard [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract			0
Recorded Investment | $			$ 0
Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract			0
Recorded Investment | $			$ 0
Commercial Real Estate [Member] | Owner-Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0
Commercial Real Estate [Member] | Nonowner-Occupied [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0
Other Commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	0	0	1
Recorded Investment | $	$ 0	$ 0	$ 1,321
Residential Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	0	0	0
Recorded Investment | $	$ 0	$ 0	$ 0
Consumer [Member] | Bankcard [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	0	0
Recorded Investment | $	$ 0	$ 0
Consumer [Member] | Other Consumer [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts | Contract	0	0
Recorded Investment | $	$ 0	$ 0