Acquisitions - Narrative (Details) - USD ($)		12 Months Ended
	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 01, 2017	Mar. 31, 2017
Business Acquisition [Line Items]
Net income		$ 28,072,000	$ 11,915,000	$ 17,297,000
Peoples Bankshares Inc [Member]
Business Acquisition [Line Items]
Percentage of ownership acquired	100.00%
Business Acquisition, Share Price, Number Of Shares	465,931
Value of assets acquired		133,000,000
Value of liabilities acquired		113,000,000
Revenues, Net of Interest Expense		3,600,000
Net income		$ 21,000
First Century Bankshares, Inc [Member]
Business Acquisition [Line Items]
Percentage of ownership acquired					100.00%
Value of assets acquired						$ 406,000,000
Value of liabilities acquired						$ 361,000,000
Cash Consideration [Member] | Peoples Bankshares Inc [Member]
Business Acquisition [Line Items]
Consideration paid in acquisition	$ 12,700,000