Fair Value of Financial Instruments - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended
	Apr. 01, 2015	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Revenue target	$ 80,000
Contingent obligation due selling unitholders of Cogent		$ 9,090		$ 15,095
Increase (decrease) in fair value contingent consideration		(6,005)	$ 385
Cogent Partners, LP
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Maximum contingent consideration	$ 18,900
Conditional consideration (shares)	334,048
Distribution period ending on the second anniversary of the closing (years)	2 years
Distribution period ending on the fourth anniversary of the closing (years)	2 years
Contingent obligation due selling unitholders of Cogent	$ 13,100	9,100
Increase (decrease) in fair value contingent consideration		$ (6,000)