Segment and Geographic Information - Summary of Segment Information (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 Information [Line Items]
Revenue	$ 288	$ 354	$ 323	$ 281	$ 213	$ 255	$ 247	$ 230	$ 1,246		$ 945		$ 763
Adjusted EBITDA									468	[1]	379	[1]	352	[1]
Depreciation									(47)	[2]	(30)	[2]	(20)	[2]
Amortization of intangible assets									(18)		(6)		(6)
Stock-based compensation									(63)		(49)		(30)
Operating income (loss)	60	84	100	96	28	84	94	88	340		294		296
Other expense, net									(18)		(10)		(14)
Income before income taxes									322		284		282
Provision for income taxes									(96)		(79)		(87)
Net income	36	54	68	68	20	56	67	62	226		205		195
Operating Segments | Hotel
Segment Reporting Information [Line Items]
Revenue									1,135		899		732
Adjusted EBITDA									472	[1]	384	[1]	349	[1]
Operating income (loss)									472		384		349
Operating Segments | Other Segment
Segment Reporting Information [Line Items]
Revenue									111		46		31
Adjusted EBITDA									(4)	[1]	(5)	[1]	3	[1]
Operating income (loss)									(4)		(5)		3
Corporate and Unallocated
Segment Reporting Information [Line Items]
Depreciation									(47)		(30)		(20)
Amortization of intangible assets									(18)		(6)		(6)
Stock-based compensation									(63)		(49)		(30)
Operating income (loss)									$ (128)		$ (85)		$ (56)

[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.