- Income Taxes (Details) € in Millions, $ in Millions		3 Months Ended			9 Months Ended		12 Months Ended
	Oct. 04, 2017 EUR (€)	Sep. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)
Income Tax Disclosure [Abstract]
Provision for income taxes		$ 508		$ 58	$ 870	$ 755
Discrete tax benefits					1,300	422
Cash taxes paid, net of refunds		200		$ 172	1,013	$ 865	$ 1,106	$ 960
Tax contingencies		$ 3,400	$ 2,300		3,400		$ 3,400
Income Tax Examination [Line Items]
Provisional tax benefit for impact of the Act			$ 789
Internal Revenue Service (IRS) | Domestic Tax Authority [Member]
Income Tax Examination [Line Items]
Tax examination, estimate of additional tax expense					$ 1,500
Luxembourg Tax Administration [Member] | Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Tax examination, estimate of additional tax expense | €	€ 250