Summary of Significant Accounting Policies - Rollforward of Unbilled Accounts Receivable (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	$ 31,187	$ 31,187
Recognized during the period		51,590
Reclassified to receivables		(49,865)
Other		597
Ending Balance	33,104	35,426
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	$ 4,193
Ending Balance		$ 34,729