Fair Value Measurements Fair Value Measurements (Change in Contingent Consideration) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 187	$ 1,737	$ 1,404	$ 2,047
Change in fair value of contingent consideration	0	0	0	(310)
Payments	0	0	(1,217)	0
Balance at end of period	$ 187	$ 1,737	$ 187	$ 1,737