Accumulated Other Comprehensive Loss and Other Comprehensive Income (Loss) - Components of accumulated other comprehensive loss (Details) - USD ($) $ in Millions	6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016
Components of Accumulated other comprehensive loss
Beginning of period	$ (1,605)	$ (1,398)
Other comprehensive income before reclassifications	67	23
Reclassified from Accumulated other comprehensive loss	52	42
Other comprehensive income	119	65
End of period	(1,486)	(1,333)
Pension and Postretirement Benefits Adjustments
Components of Accumulated other comprehensive loss
Beginning of period	(1,505)	(1,327)
Other comprehensive income before reclassifications		5
Reclassified from Accumulated other comprehensive loss	47	31
Other comprehensive income	47	36
End of period	(1,458)	(1,291)
Foreign Currency Translation Adjustments
Components of Accumulated other comprehensive loss
Beginning of period	(96)	(47)
Other comprehensive income before reclassifications	64	4
Other comprehensive income	64	4
End of period	(32)	(43)
Deferred Gains (Losses) on Hedge Contracts
Components of Accumulated other comprehensive loss
Beginning of period	(4)	(24)
Other comprehensive income before reclassifications	3	14
Reclassified from Accumulated other comprehensive loss	5	11
Other comprehensive income	8	25
End of period	$ 4	$ 1