Pension Benefits - Changes in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Thousands	3 Months Ended																	12 Months Ended
	Dec. 27, 2015		Sep. 27, 2015	[1]	Jun. 28, 2015	[1]	Mar. 29, 2015		Dec. 28, 2014		Sep. 28, 2014	[2]	Jun. 29, 2014		Mar. 30, 2014		Dec. 29, 2013	Dec. 27, 2015		Dec. 28, 2014		Dec. 29, 2013
Change in benefit obligation
Lump-sum settlement paid	$ 0	[1]	$ 0		$ 0		$ (40,329)	[1]	$ 0	[2]	$ 0		$ (9,525)	[2]	$ 0	[2]		$ (40,329)	[1]	$ (9,525)	[2]	$ (3,228)
Amount recognized in accumulated other comprehensive loss
Accumulated benefit obligation	2,090,000								2,360,000									2,090,000		2,360,000
Qualified Plans [Member]
Change in benefit obligation
Benefit obligation at beginning of year							2,101,573								1,778,647			2,101,573		1,778,647
Service cost																		11,932		9,543		11,225
Interest cost																		74,536		84,447		77,136
Plan participants’ contributions																		20		26
Actuarial (gain)/loss																		(129,187)		330,224
Curtailments																		(1,264)		0
Lump-sum settlement paid																		(98,348)		0
Benefits paid																		(107,352)		(101,314)
Effects of change in currency conversion																		0		0
Benefit obligation at end of year	1,851,910								2,101,573								$ 1,778,647	1,851,910		2,101,573		1,778,647
Change in plan assets
Fair value of plan assets at beginning of year							1,837,250								1,698,091			1,837,250		1,698,091
Actual return on plan assets																		(59,342)		225,470
Employer contributions																		7,128		14,977
Lump-sum settlement paid																		(98,348)		0
Fair value of plan assets at end of year	1,579,356								1,837,250								1,698,091	1,579,356		1,837,250		1,698,091
Amount recognized in the Consolidated Balance Sheets
Current liabilities	0								0									0		0
Noncurrent liabilities	(272,554)								(264,323)									(272,554)		(264,323)
Net amount recognized	(272,554)								(264,323)									(272,554)		(264,323)
Amount recognized in accumulated other comprehensive loss
Actuarial loss	821,648								854,267									821,648		854,267
Prior service credit	(24,621)								(26,565)									(24,621)		(26,565)
Total amount recognized in accumulated other comprehensive loss	797,027								827,702									797,027		827,702
Non-Qualified Plans [Member]
Change in benefit obligation
Benefit obligation at beginning of year							267,824								262,501			267,824		262,501
Service cost																		157		184		1,162
Interest cost																		10,060		10,450		10,681
Plan participants’ contributions																		0		0
Actuarial (gain)/loss																		(14,372)		36,604
Curtailments																		0		0
Lump-sum settlement paid																		0		(24,015)
Benefits paid																		(16,231)		(17,507)
Effects of change in currency conversion																		(351)		(393)
Benefit obligation at end of year	247,087								267,824								262,501	247,087		267,824		262,501
Change in plan assets
Fair value of plan assets at beginning of year							0								0			0		0
Actual return on plan assets																		0		0
Employer contributions																		16,231		41,522
Lump-sum settlement paid																		0		(24,015)
Fair value of plan assets at end of year	0								0								0	0		0		0
Amount recognized in the Consolidated Balance Sheets
Current liabilities	(16,043)								(15,767)									(16,043)		(15,767)
Noncurrent liabilities	(231,044)								(252,057)									(231,044)		(252,057)
Net amount recognized	(247,087)								(267,824)									(247,087)		(267,824)
Amount recognized in accumulated other comprehensive loss
Actuarial loss	100,344								119,797									100,344		119,797
Prior service credit	0								0									0		0
Total amount recognized in accumulated other comprehensive loss	100,344								119,797									100,344		119,797
Pension Plan [Member]
Change in benefit obligation
Benefit obligation at beginning of year							2,369,397								2,041,148			2,369,397		2,041,148
Service cost																		12,089		9,727		12,387
Interest cost																		84,596		94,897		87,817
Plan participants’ contributions																		20		26
Actuarial (gain)/loss																		(143,559)		366,828
Curtailments																		(1,264)		0		0
Lump-sum settlement paid							(40,300)						$ (9,500)				(3,200)	(98,348)		(24,015)
Benefits paid																		(123,583)		(118,821)
Effects of change in currency conversion																		(351)		(393)
Benefit obligation at end of year	2,098,997								2,369,397								2,041,148	2,098,997		2,369,397		2,041,148
Change in plan assets
Fair value of plan assets at beginning of year							1,837,250								$ 1,698,091			1,837,250		1,698,091
Actual return on plan assets																		(59,342)		225,470
Employer contributions																		23,359		56,499
Lump-sum settlement paid							$ (98,300)											(98,348)		(24,015)
Fair value of plan assets at end of year	1,579,356								1,837,250								$ 1,698,091	1,579,356		1,837,250		$ 1,698,091
Amount recognized in the Consolidated Balance Sheets
Current liabilities	(16,043)								(15,767)									(16,043)		(15,767)
Noncurrent liabilities	(503,598)								(516,380)									(503,598)		(516,380)
Net amount recognized	(519,641)								(532,147)									(519,641)		(532,147)
Amount recognized in accumulated other comprehensive loss
Actuarial loss	921,992								974,064									921,992		974,064
Prior service credit	(24,621)								(26,565)									(24,621)		(26,565)
Total amount recognized in accumulated other comprehensive loss	$ 897,371								$ 947,499									$ 897,371		$ 947,499

[1] We recorded a settlement charge related to a lump-sum payment offer to certain former employees who participated in a non-qualified pension plan.

[2] We recorded a settlement charge related to a lump-sum payment offer to certain former employees who participated in a non-qualified pension plan.