Equity Financing - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended	1 Months Ended
	Apr. 29, 2014	Jan. 31, 2013	Apr. 29, 2014
Equity [Abstract]
Common stock issued	2,650,000	87,000
Common stock offering price per share			$ 38.00
Net proceeds from issue of common stock	$ 94.5	$ 2.1