Summary of Significant Accounting Policies - Summary of Assumptions Used in Valuing Stock Options Granted (Detail)	1 Months Ended		12 Months Ended
	Oct. 31, 2012	Jun. 30, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2013 Minimum [Member] Employee Stock Option [Member]	Dec. 31, 2012 Minimum [Member] Employee Stock Option [Member]	Dec. 31, 2011 Minimum [Member] Employee Stock Option [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2013 Maximum [Member] Employee Stock Option [Member]	Dec. 31, 2012 Maximum [Member] Employee Stock Option [Member]	Dec. 31, 2011 Maximum [Member] Employee Stock Option [Member]
Accounting Policies [Line Items]
Risk-free interest rate			1.52%		0.08%	0.17%	0.02%	0.65%	0.96%	0.36%	0.29%	1.92%	1.49%	2.61%
Expected dividend yield			0.00%	0.00%								0.00%	0.00%	0.00%
Expected life	2 years 6 months 4 days	2 years 6 months	5 years		7 months 2 days	1 year 1 month 2 days	5 years	5 years	5 years	1 year 10 months 28 days	2 years 4 months 28 days	7 years 3 months 18 days	6 years	6 years
Expected volatility	79.70%	69.36%	75.68%		42.52%	82.75%	78.62%	86.58%	84.28%	76.03%	95.91%	89.66%	92.60%	92.38%