Annual report pursuant to Section 13 and 15(d)

Equity Incentive Plans and Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail)

v2.4.0.8
Equity Incentive Plans and Stock Based Compensation - Stock Option Activity Under Equity Incentive Plan (Detail) (USD $)
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Shares Available for Grant, Beginning Balance 498,411 1,077,784 765,848
Shares Available for Grant, Additional shares reserved 1,250,000 1,250,000 1,250,000
Shares Available for Grant, Options granted (1,663,500) (1,844,000) (1,196,500)
Shares Available for Grant, Options exercised         
Shares Available for Grant, Options canceled 90,325 14,627 258,436
Shares Available for Grant, Ending Balance 175,236 498,411 1,077,784
Number of Shares, Beginning Balance 5,098,972 3,672,179 2,745,718
Number of Shares, Granted 1,663,500 1,844,000 1,196,500
Number of Shares, Exercised (145,641) (402,580) (11,603)
Number of shares, Canceled (90,325) (14,627) (258,436)
Number of Shares, Ending Balance 6,526,506 5,098,972 3,672,179
Weighted Average Exercise Price, Beginning Balance $ 3.18 $ 1.45 $ 1.36
Weighted Average Exercise Price, Granted $ 5.10 $ 6.24 $ 1.64
Weighted Average Exercise Price, Exercised $ 1.56 $ 1.39 $ 1.24
Weighted Average Exercise Price, Canceled $ 6.49 $ 4.25 $ 1.38
Weighted Average Exercise Price, Ending Balance $ 3.66 $ 3.18 $ 1.45
Maximum [Member]
      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Weighted Average Exercise Price, Beginning Balance $ 7.75 $ 3.18 $ 3.18
Weighted Average Exercise Price, Granted $ 5.58 $ 7.75 $ 1.86
Weighted Average Exercise Price, Exercised $ 3.46 $ 3.08 $ 1.44
Weighted Average Exercise Price, Canceled $ 7.75 $ 6.18 $ 1.88
Weighted Average Exercise Price, Ending Balance $ 7.75 $ 7.75 $ 3.18
Minimum [Member]
      
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Weighted Average Exercise Price, Beginning Balance $ 0.42 $ 0.42 $ 0.42
Weighted Average Exercise Price, Granted $ 4.45 $ 1.38 $ 1.53
Weighted Average Exercise Price, Exercised $ 0.79 $ 0.79 $ 0.79
Weighted Average Exercise Price, Canceled $ 1.44 $ 0.79 $ 0.79
Weighted Average Exercise Price, Ending Balance $ 0.42 $ 0.42 $ 0.42