Common Stock - Summary of Shares Reserved for Future Issuance (Detail)	Dec. 31, 2013	Dec. 31, 2012
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Options to purchase Common Stock	5,988,732	24,811,206
Convertible Preferred Stock [Member]
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Options to purchase Common Stock
Series A Convertible Preferred Stock [Member]
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Options to purchase Common Stock		12,068,682
Series B Convertible Preferred Stock [Member]
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Options to purchase Common Stock		1,887,473
Series C Convertible Preferred Stock [Member]
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Options to purchase Common Stock		5,775,409
Options to Purchase Common Stock [Member]
Common Stock Capital Shares Reserved For Future Issuance [Line Items]
Options to purchase Common Stock	5,988,732	5,079,642