Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair market value of non-statutory options			85.00%
Increased of total number of options under the option plan			1,800,000
Stock Options Issued and Outstanding, Options Outstanding	15,859,948		15,859,948
Options expiration in period from the date of grant			10 years
Percentage of option vested at one year anniversary			25.00%
Options ratable after one year anniversary			Next 12 quarters thereafter
Option granted to purchase of common stock			1,566,750
Options outstanding weighted average exercise price	$ 5.81		$ 5.81
Common stock, Weighted average grant date fair value par share			$ 3.41
Options granted, total estimated fair value			$ 10,600,000
Aggregate intrinsic value of vested options and options expected to vest	48,200,000		48,200,000
Compensation expense related to stock options	900,000	200,000	1,400,000	500,000
Unrecognized compensation cost	9,200,000		9,200,000
Unrecognized compensation cost expected period for recognition			3 years 4 months 24 days
Income tax expense (benefit) from share based compensation			$ 0