Goodwill and Other Intangible Assets - Carrying Value and Accumulated Amortization for Each Major Class of Intangible Assets Other Than Goodwill (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	$ 1,131	$ 1,076
Accumulated Amortization	(772)	(721)
Net Carrying Amount	359	355
Carrying value and accumulated amortization for each major class of intangible assets other than goodwill
Non-amortizing intangible assets	2,649	1,254
Total intangible assets other than goodwill	3,008	1,609
Trademarks
Carrying value and accumulated amortization for each major class of intangible assets other than goodwill
Non-amortizing intangible assets	790	790
Gaming rights
Carrying value and accumulated amortization for each major class of intangible assets other than goodwill
Non-amortizing intangible assets	1,606	211
Total Rewards
Carrying value and accumulated amortization for each major class of intangible assets other than goodwill
Non-amortizing intangible assets	$ 253	253
Trade names and trademarks
Intangible Assets Excluding Goodwill [Line Items]
Weighted Average Remaining Useful Life (in years)	2 years 3 months 18 days
Gross Carrying Amount	$ 14	0
Accumulated Amortization	(1)	0
Net Carrying Amount	$ 13	0
Customer relationships
Intangible Assets Excluding Goodwill [Line Items]
Weighted Average Remaining Useful Life (in years)	4 years 8 months 12 days
Gross Carrying Amount	$ 1,071	1,030
Accumulated Amortization	(741)	(693)
Net Carrying Amount	$ 330	337
Contract rights
Intangible Assets Excluding Goodwill [Line Items]
Weighted Average Remaining Useful Life (in years)	6 years 3 months 18 days
Gross Carrying Amount	$ 3	3
Accumulated Amortization	(2)	(2)
Net Carrying Amount	$ 1	1
Gaming rights
Intangible Assets Excluding Goodwill [Line Items]
Weighted Average Remaining Useful Life (in years)	5 years 9 months 18 days
Gross Carrying Amount	$ 43	43
Accumulated Amortization	(28)	(26)
Net Carrying Amount	$ 15	$ 17