Other Real Estate Owned and Repossessed Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Changes in other real estate owned
Balance at the beginning of the period	$ 16,812	$ 9,716	$ 13,953
Additions due to acquisitions		13,227	440
Other additions	6,905	9,938	6,957
Net payments received	(1,064)	(1,560)	(45)
Disposals	(12,831)	(13,873)	(10,168)
Write-downs	(1,640)	(636)	(1,421)
Balance at the end of the period	8,182	16,812	9,716
Changes in repossessed assets
Balance at the beginning of the period	375	219	252
Additions due to acquisitions		313	0
Other additions	4,641	3,032	2,372
Net payments received	0	(763)	(22)
Disposals	(4,391)	(2,426)	(2,383)
Write-downs	0	0	0
Balance at the end of the period	$ 625	$ 375	$ 219