Schedule of Fair Value, Valuation Techniques and Related Unobservable Inputs (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Redeemable common stock		$ 18,415
Valuation Technique	Probability Weighted Expected Return Method
Discount rate		15.30%
Lack of marketability per common share		14.90%
Level 3 | Estimate of Fair Value Measurement
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Redeemable common stock		$ 18,415