Summary of Significant Accounting Policies - Recently Issued Accounting Standards (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 29, 2018	Jun. 30, 2017	Jun. 29, 2018	Jun. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative-effect adjustment to retained earnings	$ 86,383		$ 86,383			$ 85,029
Revenue	$ 92,667	$ 75,521	$ 175,380	$ 152,527
Sales Revenue [Member] | Gross Basis [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue, percent	1.40%		1.60%
ASU 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	$ 1,300		$ 2,900
ASU 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Maximum [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative-effect adjustment to retained earnings					$ 100
ASU 2014-09 [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Revenue	$ 91,400		172,500
ASU 2017-07 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Decrease in selling, general, and administrative expenses		$ 100	$ 200