Goodwill and Other Intangible Assets - Changes in Carrying Value of Goodwill and Other Intangible Assets (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Amortizing Intangible Assets
Balance as of beginning of period	$ 270
Amortization	(18)
Impairments	0
Other	0
Balance as of end of period	252
Goodwill
Balance as of beginning of period	4,012
Impairments	0
Other	(1)
Balance as of end of period	4,011
Other
Balance as of beginning of period	2,554
Impairments	(32)
Other	(2)
Balance as of end of period	2,520
Other U.S.
Goodwill [Line Items]
Goodwill of reporting unit with negative carrying value	$ 39