- Income Taxes (Details) € in Millions, $ in Millions		3 Months Ended			6 Months Ended		12 Months Ended
	Oct. 04, 2017 EUR (€)	Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)
Income Tax Disclosure [Abstract]
Provision for income taxes		$ 74		$ 467	$ 361	$ 695
Discrete tax benefits					964	197
Cash taxes paid, net of refunds		300		$ 447	813	$ 693	$ 1,077	$ 879
Tax contingencies		$ 3,300	$ 2,300		3,300		$ 3,300
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