Intangibles Asset Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2012
Customer Lists and Contracts
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets useful life, description	Lesser of 5 years or life of contract
Favorable and Assigned Leases
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets useful life, description	Life of the lease
Domain and Brand Names
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets useful life	5 years
Internally Developed Software | Minimum
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets useful life	3 years
Internally Developed Software | Maximum
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets useful life	5 years
Customer Relationship | Minimum
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets useful life	1 year
Customer Relationship | Maximum
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets useful life	3 years
Other Amortizable Intangible Assets | Minimum
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets useful life	5 years
Other Amortizable Intangible Assets | Maximum
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets useful life	10 years