Goodwill and Other Intangible Assets - Carrying Value and Accumulated Amortization for Each Major Class of Intangible Assets Other Than Goodwill (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Intangible Assets Excluding Goodwill [Line Items]
Gross Carrying Amount	$ 1,076	$ 1,076
Accumulated Amortization	(754)	(721)
Net Carrying Amount	322	355
Carrying value and accumulated amortization for each major class of intangible assets other than goodwill
Non-amortizing intangible assets	1,251	1,254
Intangible assets other than goodwill	1,573	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	208	211
Total Rewards
Carrying value and accumulated amortization for each major class of intangible assets other than goodwill
Non-amortizing intangible assets	$ 253	253
Customer relationships
Intangible Assets Excluding Goodwill [Line Items]
Weighted Average Remaining Useful Life (in years)	4 years 6 months
Gross Carrying Amount	$ 1,030	1,030
Accumulated Amortization	(725)	(693)
Net Carrying Amount	$ 305	337
Contract rights
Intangible Assets Excluding Goodwill [Line Items]
Weighted Average Remaining Useful Life (in years)	6 years 6 months
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)	6 years
Gross Carrying Amount	$ 43	43
Accumulated Amortization	(27)	(26)
Net Carrying Amount	$ 16	$ 17