Fair Value Measurements Fair Value Measurements (Change in contingent consideration) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 1,404	$ 2,047
Change in fair value of contingent consideration liability	(187)	(643)	$ (898)
Payments	(1,217)	0
Ending Balance	$ 0	$ 1,404	$ 2,047