Mergers and Acquisitions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Sep. 09, 2016	Dec. 31, 2016	Dec. 31, 2015
Your Community Bankshares, Inc [Member]
Business Acquisition [Line Items]
Total assets acquired, excluding goodwill	$ 1,500,000
Loans	1,013,566
Securities	173,223
Value of acquisition	$ 220,498
Common shares issued	5,423,348
Cash consideration for outstanding YCB shares	$ 43,349
Goodwill acquired	92,889	$ 92,900
Purchase price allocation in core deposit intangible	$ 11,957
Closing stock price	$ 32.62
Merger related expense		$ 13,300
Common Stock [Member]
Business Acquisition [Line Items]
Common shares issued		5,423,348	9,178,531
Common Stock [Member] | Your Community Bankshares, Inc [Member]
Business Acquisition [Line Items]
Common shares issued	5,423,348
Cash consideration for outstanding YCB shares	$ 43,300