Property and Equipment, Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2012
Office Equipment
Finite-Lived Intangible Assets [Line Items]
Property and equipment useful life	5 years
Automobiles
Finite-Lived Intangible Assets [Line Items]
Property and equipment useful life	5 years
Furniture and Fixtures | Minimum
Finite-Lived Intangible Assets [Line Items]
Property and equipment useful life	5 years
Furniture and Fixtures | Maximum
Finite-Lived Intangible Assets [Line Items]
Property and equipment useful life	7 years
Leasehold Improvements
Finite-Lived Intangible Assets [Line Items]
Property and equipment useful life	Shorter of length of lease or 10 years