Depreciation and Amortization Periods for Company's Property and Equipment (Detail)	12 Months Ended
	Dec. 31, 2012
Computer Equipment
Property Plant and Equipment Estimated Useful Lives [Line Items]
Property plant and Equipment useful life	3 years
Computer Software
Property Plant and Equipment Estimated Useful Lives [Line Items]
Property plant and Equipment useful life	3 years
Furniture and Fixtures
Property Plant and Equipment Estimated Useful Lives [Line Items]
Property plant and Equipment useful life	3 years
Leasehold Improvements
Property Plant and Equipment Estimated Useful Lives [Line Items]
Property plant and Equipment useful life, description	Shorter of the estimated useful life or remaining term of lease