Income Taxes (Uncertain Tax Positions) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, income tax penalties and interest accrued	$ 400	$ 200	$ 500
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1	2,832	2,996	2,441
Additions based on current year tax positions	381	211	117
Changes for tax positions of prior years	(152)
Changes for tax positions of prior years		96	160
Settlements	58		19
Settlements		(155)
Additions due to acquired business	0	0	954
Reductions due to lapses in statutes of limitation	0	(124)	(375)
Balance at December 31	3,423	2,832	2,996
Unrecognized tax benefits that would impact effective tax rate	3,000
Unrecognized tax benefits, income tax penalties and interest expense ($0.1 million or less)	100	100	100
Income taxes paid, net	$ 16,600	$ 24,800	$ 35,700