Acquisitions - Summary of Purchase Price Allocation Initially Recorded on Unaudited Condensed Consolidated Balance Sheet for all Acquisitions (Parenthetical) (Details) - Series of Individually Immaterial Business Acquisitions $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($)
Business Acquisition [Line Items]
Intangible assets	$ 22	[1]
Weighted average life of identifiable definite-lived intangible assets acquired	6 years 3 months 18 days
Cash acquired from acquisition	$ 3
Trade Names
Business Acquisition [Line Items]
Intangible assets	$ 4
Weighted average life of identifiable definite-lived intangible assets acquired	10 years
Developed Technology and Other
Business Acquisition [Line Items]
Intangible assets	$ 18
Weighted average life of identifiable definite-lived intangible assets acquired	5 years 3 months 18 days
Hotel Segment
Business Acquisition [Line Items]
Acquired goodwill not deductible for tax purposes	$ 10
Non-Hotel Segment
Business Acquisition [Line Items]
Acquired goodwill not deductible for tax purposes	$ 3

[1] Identifiable definite-lived intangible assets acquired during 2016 were comprised of trade names of $4 million with a weighted average life of 10.0 years and technology and other of $18 million with a weighted average life of 5.3 years. The overall weighted-average life of the identifiable definite-lived intangible assets acquired in the purchase of these businesses during 2016 was 6.3 years, and will be amortized on a straight-line basis over their estimated useful lives from acquisition date.