Common Stock and Preferred Stock - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended				12 Months Ended											12 Months Ended
	Dec. 31, 2013 Stock	Dec. 31, 2012	Dec. 31, 2011	Jun. 25, 2013	Dec. 31, 2013 Series A Preferred Stock [Member]	Dec. 31, 2012 Series A Preferred Stock [Member]	Dec. 31, 2013 Series B Preferred Stock [Member]	Dec. 31, 2012 Series B Preferred Stock [Member]	Dec. 31, 2013 Series C Preferred Stock [Member]	Dec. 31, 2012 Series C Preferred Stock [Member]	Dec. 31, 2013 Series D Preferred Stock [Member]	Dec. 31, 2012 Series D Preferred Stock [Member]	Dec. 31, 2013 Series E Preferred Stock [Member]	Dec. 31, 2012 Series E Preferred Stock [Member]	Apr. 30, 2013 Series E Preferred Stock [Member]	Dec. 31, 2013 Mandatorily Redeemable Convertible Preferred Stock [Member]
Common And Preferred Stock [Line Items]
Conversion of Convertible Preferred Stock Into Common Stock, Shares	8,631,427	8,631,427			(557,339)		(515,836)		(3,551,060)		(2,430,054)		(1,063,951)
Each share of common stock is entitled to vote	1
Preferred stock, shares authorized	15,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0		0
Redemption terms																At any time after November 29, 2017 and upon 30 day notice from the holders of 65% of the outstanding Preferred Stock
Preferred stock, redemption date																Nov. 29, 2017
Preferred stock, redemption notice period																30 days
Holders outstanding preferred stock																65.00%
Accretion of mandatorily redeemable convertible preferred stock	$ 4,653	$ 7,533	$ 5,251
Preferred Stock, redemption rate	8.00%
Preferred stock converted into common stock on a basis						1.403030-for-one basis		1.559429-for-one basis		One-for-one basis		One-for-one basis		One-for-one basis
Warrants to purchase convertible preferred stock														604,563
Shares of convertible preferred stocks called by warrants															10,418
Preferred stock warrants, exercisable period															10 years
Preferred stock warrants were converted into warrants to purchase common stock	617,605
Exercise price of common stock warrants	$ 8.78