Income Taxes - Schedule of Changes in Valuation Allowance (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Valuation Allowance [Line Items]
Balance at beginning of year	$ 2,486	$ 2,584	$ 1,940
Increase to allowance	37	136	831
Release of allowance	(222)	(154)	(246)
Acquisitions and divestitures (F)	(2)	0	(1)
Tax apportionment, tax rate and tax law changes	(13)	(14)	(24)
Foreign currency translation	(30)	(66)	84
Balance at end of year	2,256	2,486	$ 2,584
Other Net State Deferred Tax Asset
Valuation Allowance [Line Items]
Balance at beginning of year	$ 672
Balance at end of year		$ 672