Goodwill and Other Intangible Assets - Changes in Goodwill and Other Intangible Assets (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($)
Goodwill and Other Intangible Assets [Roll Forward]
Amortizing Intangible Assets, Beginning Balance	$ 342
Amortizing Intangible Assets, Amortization expense	18
Goodwill, Impairment Loss	0
Impairment of Intangible Assets (Excluding Goodwill)	0
Amortizing Intangible Assets, Ending Balance	324
Goodwill, Beginning Balance	4,044
Goodwill, Other Increase (Decrease)	0
Goodwill, Ending Balance	4,044
Other Non-Amortizing Intangible Assets, Beginning Balance	2,635
Other Non-Amortizing Intangible Assets, Ending Balance	2,637
Other Intangible Assets [Member]
Goodwill and Other Intangible Assets [Roll Forward]
Amortizing Intangible Assets, Amortization expense	0
Other Intangible Assets [Member]
Goodwill and Other Intangible Assets [Roll Forward]
Other Non-Amortizing Intangible Assets, Beginning Balance	253
Indefinite-lived Intangible Assets	2
Other Non-Amortizing Intangible Assets, Ending Balance	$ 253