Stockholders Equity - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	9 Months Ended
	Aug. 04, 2011	Sep. 30, 2013	Dec. 31, 2012
Stockholders Equity Note [Abstract]
Common stock reserved for future grants of stock options		1,924,381
Common stock reserved for issuance upon exercise of outstanding common stock options		2,334,782
Common stock reserved for future exercise of outstanding warrants		267,826
Common stock warrants exercised
Common stock warrants outstanding		267,826	267,826
Stock repurchase program, authorized amount	$ 25.0
Stock repurchase program, period	2 years
Repurchase of company shares		0