Postretirement Benefit Plans - Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Loss) Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 28, 2014	Dec. 29, 2013	Dec. 30, 2012
Comprehensive Income (Loss) [Line Items]
Current year actuarial loss	$ 500,389	$ (286,778)	$ 230,799
Change in prior service (costs) credit	(37,986)	(319)	0
Amortization of actuarial loss	(46,489)	(64,381)	(55,372)
Pension and other postretirement benefit items	396,368	(342,798)	190,357
Other Postretirement Benefit Plans, Defined Benefit
Comprehensive Income (Loss) [Line Items]
Current year actuarial loss	(7,265)
Change in prior service (costs) credit	37,986
Amortization of actuarial loss	758
Amortization of prior service costs	(11,648)	(9,165)	(19,190)
Pension and other postretirement benefit items	$ 19,831

Amount before tax of cost (credit) of benefit changes attributable to plan participants' prior service resulting from a plan amendment or plan initiation that has not been recognized in net periodic benefit cost (credit).

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Amount before tax of (increase) decrease in the value of the projected benefit obligation related to a change in an actuarial assumption and increase (decrease) in the value of the plan assets resulting from experience different from that assumed, that has not been recognized in net periodic benefit (cost) credit.

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- Definition

Amount before tax of reclassification adjustment from accumulated other comprehensive income (loss) for actuarial gain (loss) related to pension and other postretirement benefit plans.

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