Revenue from Contracts with Customers - Change in Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019
Contract assets increase (decrease)
Contract assets recognized	$ 358	$ 1,313
Reclassification of contract assets to contra-revenue	(492)	(328)
Net change	(134)	985
Contract liabilities (increase) decrease
Contract liabilities recognized and recorded to contra-revenue as a result of performance obligations satisfied	(88,981)	(110,789)
Contract liabilities paid	102,985	109,592
Cash received in advance and not recognized as revenue	(68,840)	(49,962)
Reclassification of cash received in advance to revenue as a result of performance obligations satisfied	58,316	51,554
Net change	$ 3,480	$ 395