Shareholders' Equity - Components of accumulated other comprehensive income (loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Jan. 02, 2016
Components of Accumulated other comprehensive loss
Beginning of the period	$ (1,398)	$ (1,506)
Other comprehensive income (loss) before reclassifications	(282)	1
Reclassified from Accumulated other comprehensive loss	75	107
Other comprehensive income (loss)	(207)	108
End of the period	(1,605)	(1,398)
Pension and Postretirement Benefits Adjustments
Components of Accumulated other comprehensive loss
Beginning of the period	(1,327)	(1,511)
Other comprehensive income (loss) before reclassifications	(240)	92
Reclassified from Accumulated other comprehensive loss	62	92
Other comprehensive income (loss)	(178)	184
End of the period	(1,505)	(1,327)
Foreign Currency Translation Adjustments
Components of Accumulated other comprehensive loss
Beginning of the period	(47)	18
Other comprehensive income (loss) before reclassifications	(49)	(65)
Other comprehensive income (loss)	(49)	(65)
End of the period	(96)	(47)
Deferred Gains (Losses) on Hedge Contracts
Components of Accumulated other comprehensive loss
Beginning of the period	(24)	(13)
Other comprehensive income (loss) before reclassifications	7	(26)
Reclassified from Accumulated other comprehensive loss	13	15
Other comprehensive income (loss)	20	(11)
End of the period	$ (4)	$ (24)