Revenue - Subscription, Advertising, and Other Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jun. 25, 2017	Jul. 01, 2018	Jun. 25, 2017
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 414,560	$ 407,074	$ 828,508	$ 805,878
Rental income, not subject to ASC 606	6,000	4,000	10,000	8,000
Subscription
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	260,629	250,037	521,222	492,412
Advertising
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	119,201	132,234	244,848	262,262
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 34,730	$ 24,803	$ 62,438	$ 51,204