Subsequent Events - Additional Information (Detail) (Subsequent Event, USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
	Sep. 17, 2014	Sep. 17, 2014
Subsequent Event [Line Items]
Underwritten public offering, number of common stock closed	4,682,927
Underwritten public offering, price per share		$ 10.25
Underwriters' option to purchase additional shares to cover over-allotments, duration	30 days
Underwritten public offering net of underwriting discounts and commissions and offering expenses	$ 52.4
Repayment of portion of outstanding principal	$ 20
Additional
Subsequent Event [Line Items]
Underwritten public offering, number of common stock closed	702,439