Recent Developments Including Mergers and Acquisitions - Additional Information (Detail) - USD ($)			1 Months Ended
	Mar. 05, 2020	Aug. 15, 2019	Jan. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Business Combination Separately Recognized Transactions [Line Items]
Goodwill				$ 149,923,000	$ 148,604,000
Gain on sale of property held in other real estate owned			$ 2,200,000
Citizens Bankshares, Inc [Member]
Business Combination Separately Recognized Transactions [Line Items]
Date of acquisition	Mar. 05, 2020
Total assets acquired	$ 47,800,000
Loans	22,900,000
Deposits	45,000,000.0
Certain other obligations	2,900,000
Intangibles assets, net	206,000
Goodwill	$ 1,300,000
Pegasus Bank [Member]
Business Combination Separately Recognized Transactions [Line Items]
Date of acquisition		Aug. 15, 2019