Postretirement Benefit Plans - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 27, 2016	Mar. 29, 2015
Defined Benefit Plan Disclosure [Line Items]
Recognition of previously deferred postretirement benefit plan amounts, net of tax	$ 173,000,000	$ 212,000,000
Recognition of previously deferred postretirement benefit plan amounts, tax	95,000,000	116,000,000
Other postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Recognition of previously deferred postretirement benefit plan amounts, before tax	11,000,000	13,000,000
Heritage Qualified Defined Benefit Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Contributions made by the employer	$ 0	$ 0