Fair Value Measurements - Liability Measured on Recurring Basis, Unobservable Input Reconciliation (Details) - Contingent Consideration - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 898	$ 1,949	$ 1,024	$ 1,886
Contingent consideration liability recorded as the result of acquisitions (see Note 5)	0	270	0	270
Fair value adjustments recorded to income during the period	(193)	(58)	(136)	185
Contingent payments made	(16)	(14)	(199)	(194)
Ending balance	$ 689	$ 2,147	$ 689	$ 2,147