Revenue - Subscription, Advertising, and Other Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 428,501	$ 417,346	$ 1,303,821	$ 1,245,854
Subscription
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	267,302	257,796	808,568	779,018
Advertising
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	113,531	121,677	359,380	366,525
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	47,668	37,873	135,873	100,311
Real Estate
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 8,000	$ 7,000	$ 23,000	$ 17,000