Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes
Federal corporate income tax rate	21.00%	35.00%	35.00%
Incremental income tax expense for remeasurement of deferred tax asset		$ 6,640
Deferred tax asset
Allowance for loan losses and OREO losses	$ 8,567	9,004
Fair value adjustments related to business combinations	1,643	2,123
Nonqualified defined contribution plan	2,925	2,460
Share-based compensation	825	769
Reserve for indemnification losses	663	641
Interest on nonaccrual loans	346	475
Net unrealized loss on securities available for sale	365
Other	1,415	1,286
Deferred tax asset	16,749	16,758
Deferred tax liability
Goodwill and other intangible assets	(2,838)	(2,886)
Depreciation	(1,024)	(632)
Defined benefit plan	(620)	(934)
Cash flow hedges	(74)	(43)
Net unrealized gain on securities available for sale		(170)
Deferred tax liability	(4,556)	(4,665)
Net deferred tax asset	$ 12,193	$ 12,093