Other Real Estate Owned - Summary of Other Real Estate Owned (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Real Estate [Abstract]
Balance at beginning of period		$ 7,403	$ 11,641	$ 7,259
Transfers from loans		3,605	2,724	4,085
Transfers from premises and equipment	$ 3,466	3,466
Capital improvements				171
Acquired through merger or acquisition		6,888		5,002
Properties sold		(5,438)	(6,696)	(3,774)
Gain on sale of other real estate owned		1,080	1,670	187
Transferred to loans		(256)	(1,548)	(785)
Write-downs and partial liquidations		(306)	(388)	(504)
Balance at end of period	$ 16,442	$ 16,442	$ 7,403	$ 11,641