Acquisitions - Summary of Purchase Price Allocation Initially Recorded on Unaudited Condensed Consolidated Balance Sheet for all Acquisitions (Details) - USD ($) $ in Millions		Sep. 30, 2016	Dec. 31, 2015
Business Acquisition [Line Items]
Goodwill		$ 744	$ 732
Series of Individually Immaterial Business Acquisitions
Business Acquisition [Line Items]
Goodwill	[1]	13
Intangible assets	[2]	22
Net liabilities assumed	[3]	(8)
Total purchase price consideration	[4]	$ 27

[1] Acquired goodwill of $10 million and $3 million was allocated to our Hotel and Non-Hotel segment, respectively. All goodwill is not deductible for tax purposes.

[2] 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.

[3] Includes cash acquired of $3 million.

[4] Subject to adjustment based on (i) final working capital adjustment calculations to be determined for CityMaps, and (ii) indemnification obligations for general representations and warranties of the acquired company stockholders.