Accounting Policies - Revenue, Initial Application Period Cumulative Effect Transition (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net service sales	$ 21,022	$ 13,210	$ 40,460	$ 25,190
Net product sales	31,864	24,745	63,468	48,479
Cost of sales	$ 30,632	$ 23,451	61,367	$ 45,891
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Subscription Services [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net service sales			1,700
Net product sales			(1,700)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Other Services [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net service sales			1,200
Cost of sales			$ 1,200