Shareholders' Equity - Before and after-tax components of other comprehensive income (loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Pension and postretirement benefits adjustments, pre-tax:
Amortization of net actuarial loss, pre-tax	$ 39	$ 34	$ 77	$ 68
Amortization of prior service cost, pre-tax	2	2	4	4
Pension and postretirement benefits adjustments, net, pre-tax	41	36	81	72
Deferred gains (losses) on hedge contracts, pre-tax:
Current deferrals, pre-tax	(4)	2	(2)	5
Reclassification adjustments, pre-tax	(1)	4	(1)	6
Deferred gains (losses) on hedge contracts, net, pre-tax	(5)	6	(3)	11
Foreign currency translation adjustments, pre-tax	(66)	39	(26)	60
Other comprehensive income (loss), pre-tax	(30)	81	52	143
Pension and postretirement benefits adjustments, tax:
Amortization of net actuarial loss, tax	(9)	(12)	(18)	(24)
Amortization of prior service cost, tax	(1)	(1)	(1)	(1)
Pension and postretirement benefits adjustments, net, tax	(10)	(13)	(19)	(25)
Deferred gains (losses) on hedge contracts, tax:
Current deferrals, tax	1	(1)		(2)
Reclassification adjustments, tax		(1)		(1)
Deferred gains (losses) on hedge contracts, net, tax	1	(2)		(3)
Foreign currency translation adjustments, tax	(3)	3	(1)	4
Other comprehensive income (loss), tax	(12)	(12)	(20)	(24)
Pension and postretirement benefits adjustments, after-tax:
Amortization of net actuarial loss, after-tax	30	22	59	44
Amortization of prior service cost, after-tax	1	1	3	3
Pension and postretirement benefits adjustments, net, after-tax	31	23	62	47
Deferred gains (losses) on hedge contracts, after-tax:
Current deferrals, after-tax	(3)	1	(2)	3
Reclassification adjustments, after-tax	(1)	3	(1)	5
Deferred gains (losses) on hedge contracts, net, after-tax	(4)	4	(3)	8
Foreign currency translation adjustments, after-tax	(69)	42	(27)	64
Other comprehensive income (loss)	$ (42)	$ 69	$ 32	$ 119