Subsequent Events - Additional Information (Detail) - Subsequent Event $ / shares in Units, $ in Millions	Oct. 09, 2015 USD ($) $ / shares shares
Subsequent Event [Line Items]
Common stock issued	3,250,000
Common stock price per share | $ / shares	$ 39.00
Period granted to underwriters to purchase of additional shares	30 days
Common stock available for sale	487,500
Net proceeds from issue of common stock | $	$ 120.0