Summary of Significant Accounting Policies - Rollforward of Unbilled Accounts Receivable (Details) - USD ($) $ in Thousands		6 Months Ended
	Jan. 01, 2018	Jun. 30, 2018
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Beginning Balance	$ 31,187	$ 33,104
Recognized during the period		111,549
Reclassified to receivables		(104,913)
Other		(908)
Ending Balance	33,104	$ 38,832
ASC 606
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification - Adoption of ASC 606	(2,276)
ASC 606 | Unbilled Receivables
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect adjustments	$ 4,193