Pension Benefits - Changes in Benefit Obligation and Plan Assets (Details) - USD ($) $ in Thousands	3 Months Ended																	12 Months Ended
	Dec. 25, 2016		Sep. 25, 2016	[1]	Jun. 26, 2016	[1]	Mar. 27, 2016		Dec. 27, 2015		Sep. 27, 2015	[2]	Jun. 28, 2015	[2]	Mar. 29, 2015		Jun. 29, 2014	Dec. 25, 2016		Dec. 27, 2015		Dec. 28, 2014
Change in benefit obligation
Lump-sum settlement paid	$ (21,294)	[1]	$ 0		$ 0		$ 0	[1]	$ 0	[2]	$ 0		$ 0		$ (40,329)	[2]		$ (21,294)	[1]	$ (40,329)	[2]	$ (9,525)
Amount recognized in accumulated other comprehensive loss
Accumulated benefit obligation	2,000,000								2,100,000									2,000,000		2,100,000
Qualified Plans [Member]
Change in benefit obligation
Benefit obligation at beginning of year							1,851,910								2,101,573			1,851,910		2,101,573
Service cost																		8,991		11,932		9,543
Interest cost																		66,293		74,536		84,447
Plan participants’ contributions																		9		20
Actuarial (gain)/loss																		23,994		(129,187)
Curtailments																		0		(1,264)
Lump-sum settlement paid																		(48,413)		(98,348)
Benefits paid																		(104,132)		(107,352)
Effects of change in currency conversion																		0		0
Benefit obligation at end of year	1,798,652								1,851,910									1,798,652		1,851,910		2,101,573
Change in plan assets
Fair value of plan assets at beginning of year							1,579,356								1,837,250			1,579,356		1,837,250
Actual return on plan assets																		142,137		(59,342)
Employer contributions																		7,803		7,128
Lump-sum settlement paid																		(48,413)		(98,348)
Fair value of plan assets at end of year	1,576,760								1,579,356									1,576,760		1,579,356		1,837,250
Amount recognized in the Consolidated Balance Sheets
Current liabilities	0								0									0		0
Noncurrent liabilities	(221,892)								(272,554)									(221,892)		(272,554)
Net amount recognized	(221,892)								(272,554)									(221,892)		(272,554)
Amount recognized in accumulated other comprehensive loss
Actuarial loss	765,096								821,648									765,096		821,648
Prior service credit	(22,676)								(24,621)									(22,676)		(24,621)
Total amount recognized in accumulated other comprehensive loss	742,420								797,027									742,420		797,027
Non-Qualified Plans [Member]
Change in benefit obligation
Benefit obligation at beginning of year							247,087								267,824			247,087		267,824
Service cost																		143		157		184
Interest cost																		8,172		10,060		10,450
Plan participants’ contributions																		0		0
Actuarial (gain)/loss																		2,695		(14,372)
Curtailments																		(1,599)		0
Lump-sum settlement paid																		0		0
Benefits paid																		(15,992)		(16,231)
Effects of change in currency conversion																		(107)		(351)
Benefit obligation at end of year	240,399								247,087									240,399		247,087		267,824
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																		15,992		16,231
Lump-sum settlement paid																		0		0
Fair value of plan assets at end of year	0								0									0		0		0
Amount recognized in the Consolidated Balance Sheets
Current liabilities	(16,818)								(16,043)									(16,818)		(16,043)
Noncurrent liabilities	(223,581)								(231,044)									(223,581)		(231,044)
Net amount recognized	(240,399)								(247,087)									(240,399)		(247,087)
Amount recognized in accumulated other comprehensive loss
Actuarial loss	98,855								100,344									98,855		100,344
Prior service credit	0								0									0		0
Total amount recognized in accumulated other comprehensive loss	98,855								100,344									98,855		100,344
Pension Plan [Member]
Change in benefit obligation
Benefit obligation at beginning of year							2,098,997								2,369,397			2,098,997		2,369,397
Service cost																		9,134		12,089		9,727
Interest cost																		74,465		84,596		94,897
Plan participants’ contributions																		9		20
Actuarial (gain)/loss																		26,689		(143,559)
Curtailments																		(1,599)		(1,264)
Lump-sum settlement paid	(21,300)														(40,300)		$ (9,500)	(48,413)		(98,348)
Benefits paid																		(120,124)		(123,583)
Effects of change in currency conversion																		(107)		(351)
Benefit obligation at end of year	2,039,051								2,098,997									2,039,051		2,098,997		2,369,397
Change in plan assets
Fair value of plan assets at beginning of year							$ 1,579,356								$ 1,837,250			1,579,356		1,837,250
Actual return on plan assets																		142,137		(59,342)
Employer contributions																		23,795		23,359
Lump-sum settlement paid																		(48,413)		(98,348)
Fair value of plan assets at end of year	1,576,760								1,579,356									1,576,760		1,579,356		$ 1,837,250
Amount recognized in the Consolidated Balance Sheets
Current liabilities	(16,818)								(16,043)									(16,818)		(16,043)
Noncurrent liabilities	(445,473)								(503,598)									(445,473)		(503,598)
Net amount recognized	(462,291)								(519,641)									(462,291)		(519,641)
Amount recognized in accumulated other comprehensive loss
Actuarial loss	863,951								921,992									863,951		921,992
Prior service credit	(22,676)								(24,621)									(22,676)		(24,621)
Total amount recognized in accumulated other comprehensive loss	$ 841,275								$ 897,371									$ 841,275		$ 897,371

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

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