Summary of Significant Accounting Policies - Recently Issued Accounting Standards (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 29, 2017	Sep. 29, 2017	Sep. 30, 2016	Mar. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification of deferred tax current assets to non-current assets				$ 900	$ 900
Taxes remitted for shares withheld from equity-based compensation transactions		$ 285	$ 347
ASU 2016-09 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Additional tax expense	$ 200	300
Taxes remitted for shares withheld from equity-based compensation transactions		$ 300	$ 300
Sales Revenue, Net [Member] | Time and Material or Progress Billing Method of Accounting [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue, percent		96.80%
Sales Revenue, Net [Member] | Proportional Method of Accounting [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue, percent		3.20%