Revenue - Advertising Revenues (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Apr. 01, 2018
Disaggregation of Revenue [Line Items]
Advertising revenue	$ 439,062	$ 413,948
Display
Disaggregation of Revenue [Line Items]
Advertising revenue	104,454	109,505
Other
Disaggregation of Revenue [Line Items]
Advertising revenue	20,634	16,142
Total advertising
Disaggregation of Revenue [Line Items]
Advertising revenue	125,088	125,647
Print | Display
Disaggregation of Revenue [Line Items]
Advertising revenue	62,342	70,805
Print | Other
Disaggregation of Revenue [Line Items]
Advertising revenue	7,203	8,139
Print | Total advertising
Disaggregation of Revenue [Line Items]
Advertising revenue	69,545	78,944
Digital | Display
Disaggregation of Revenue [Line Items]
Advertising revenue	42,112	38,700
Digital | Other
Disaggregation of Revenue [Line Items]
Advertising revenue	13,431	8,003
Digital | Total advertising
Disaggregation of Revenue [Line Items]
Advertising revenue	$ 55,543	$ 46,703