Other Postretirement Benefits - Other Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 25, 2016	Dec. 27, 2015	Dec. 28, 2014	Dec. 29, 2013
Other Postretirement Benefits
Postemployment benefits liability		$ 12,900	$ 15,900
Unrecognized prior service cost due to change in plan provisions			(25,500)
Unrecognized (gain)/loss due to change in discount rate			3,600
Total effect of other postretirement benefit changes			21,900
Increase in postretirement benefit obligation due to changes in mortality assumptions		4,200
Other Postretirement Benefit Plans, Defined Benefit [Member]
Other Postretirement Benefits
Effect of curtailment		$ 0	$ 0	$ 49,122
New England Media Group [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Other Postretirement Benefits
Effect of curtailment				$ 49,100
Scenario, Forecast [Member]
Other Postretirement Benefits
Service and interest costs	$ (18,100)
Scenario, Forecast [Member] | Other Postretirement Benefit Plans, Defined Benefit [Member]
Other Postretirement Benefits
Service and interest costs	$ 700
Minimum [Member] | Scenario, Forecast [Member]
Other Postretirement Benefits
Spot rate used in calculation of service and interest costs	0.84%
Maximum [Member] | Scenario, Forecast [Member]
Other Postretirement Benefits
Spot rate used in calculation of service and interest costs	5.18%