Pension Benefits - Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income (Details) (USD $)	12 Months Ended
	Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012
Pension Benefits
Defined contribution plan, cost recognized	$ 17,000,000	$ 18,000,000	$ 18,000,000
Pension Plans, Defined Benefit [Member]
Pension Benefits
Net actuarial loss/(gain)	254,525,000	(178,088,000)	96,551,000
Prior service credit	0	0	(31,839,000)
Amortization of loss	(30,665,000)	(39,017,000)	(37,813,000)
Amortization of prior service cost/(credit)	1,945,000	1,945,000	(574,000)
Effect of settlement	(9,525,000)	(3,358,000)	(47,657,000)
Total recognized in other comprehensive loss/(income)	216,280,000	(218,518,000)	(21,332,000)
Net periodic pension cost	29,703,000	16,568,000	82,702,000
Total recognized in net periodic benefit cost and other comprehensive loss	245,983,000	(201,950,000)	61,370,000
Estimated actuarial loss that will be amortized from accumulated other comprehensive loss into net periodic pension cost over the next fiscal year	40,000,000
Estimated prior service credit that will be amortized from accumulated other comprehensive loss into net periodic pension cost over the next fiscal year	$ 2,000,000