Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Significant Accounting Policies [Line Items]
Redeemable noncontrolling interest		$ 13	$ 14
Advertising expense		870	796	694
Prepaid marketing expenses		$ 9	$ 11
EXPE's percentage of third party service provider total revenue	34.00%		38.00%
Stock Options
Significant Accounting Policies [Line Items]
Vesting period		4 years
Restricted Stock Units (RSUs)
Significant Accounting Policies [Line Items]
Vesting period		5 years
Minimum
Significant Accounting Policies [Line Items]
Definite lived intangible assets, estimated useful life		1 year
Maximum
Significant Accounting Policies [Line Items]
Definite lived intangible assets, estimated useful life		12 years
Computer Equipment | Minimum
Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		3 years
Computer Equipment | Maximum
Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		5 years
Software Development | Minimum
Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		3 years
Software Development | Maximum
Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		5 years
Furniture and Fixtures | Minimum
Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		3 years
Furniture and Fixtures | Maximum
Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives		5 years
Airasia Joint Venture
Significant Accounting Policies [Line Items]
Owned equity investments		50.00%