Summary of Significant Accounting Policies - Rollforward of Deferred Revenue (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 01, 2018	Mar. 31, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Beginning Balance	$ (54,231)	$ (54,231)
Revenue recognized that was included in deferred revenue at the beginning of the period		19,405
Consideration received in advance of services performed net of revenue recognized in the current period		(18,237)
Other		(945)
Ending Balance	(47,611)	(47,388)
ASU 606
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification - Adoption of ASC 606	2,276
ASU 606 | Calculated under Revenue Guidance in Effect before Topic 606
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect adjustments	$ 4,344
Ending Balance		$ (51,169)