Stockholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended	9 Months Ended
	Mar. 26, 2014	Sep. 30, 2014	Sep. 30, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from public offering of common stock, net of issuance costs	$ 93,796	$ 93,796	$ 69,492
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Public offering, common stock shares issued	4,444,444
Public offering price of common stock issued	$ 22.50