Supplemental Stockholders' Equity Information Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 25, 2017	Jun. 26, 2016	Jun. 25, 2017	Jun. 26, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 25, 2016			$ (479,816)
Income tax expense	$ 3,826	$ 2,477	7,357	$ 5,580
Other comprehensive income, net of tax	5,990	$ 3,938	11,555	9,029
Balance as of June 25, 2017	(468,261)		(468,261)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 25, 2016			(1,822)
Other comprehensive income before reclassifications, before tax			5,071
Amounts reclassified from accumulated other comprehensive loss, before tax			0
Income tax expense			1,885
Other comprehensive income, net of tax			3,186
Balance as of June 25, 2017	1,364		1,364
Funded Status of Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 25, 2016			(477,994)
Other comprehensive income before reclassifications, before tax			0
Amounts reclassified from accumulated other comprehensive loss, before tax			13,841
Income tax expense			5,472
Other comprehensive income, net of tax			8,369
Balance as of June 25, 2017	(469,625)		(469,625)
Total Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 25, 2016			(479,816)
Other comprehensive income before reclassifications, before tax			5,071
Amounts reclassified from accumulated other comprehensive loss, before tax			13,841
Income tax expense			7,357
Other comprehensive income, net of tax			11,555	$ 9,029
Balance as of June 25, 2017	$ (468,261)		$ (468,261)