Segment and Geographic Information - Reconciliation of Adjusted EBITDA to Net Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Segment Reporting [Abstract]
Adjusted EBITDA									$ 468	[1]	$ 379	[1]	$ 352	[1]
Depreciation									(47)	[2]	(30)	[2]	(20)	[2]
OIBA									421	[3]	349	[3]	332	[3]
Amortization of intangible assets									(18)		(6)		(6)
Stock-based compensation									(63)		(49)		(30)
Other expense, net									(18)		(10)		(14)
Provision for income taxes									(96)		(79)		(87)
Net income	$ 36	$ 54	$ 68	$ 68	$ 20	$ 56	$ 67	$ 62	$ 226		$ 205		$ 195

[1] Includes allocated general and administrative expenses in our Hotel segment of $87 million, $72 million and $56 million; and in our Other segment of $18 million, $9 million and $6 million for the years ended December 31, 2014, 2013 and 2012, respectively.

[2] Includes amortization of internal use software and website development costs.

[3] We define OIBA as net income (loss) plus: (1) provision for income taxes; (2) other income (expense), net; (3) stock-based compensation; (4) amortization of intangible assets; and (5) non-recurring expenses. This operating metric is only used by our management to calculate our annual obligation for our charitable foundation. Refer to “Note 12— Commitments and Contingencies” for a discussion of our charitable foundation.