Repurchase of Common Stock - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	6 Months Ended	9 Months Ended
	Oct. 31, 2013	Nov. 30, 2013	Feb. 28, 2014
Equity, Class of Treasury Stock [Line Items]
Stock Repurchase Program, Authorized Amount	$ 25
Stock Repurchased and Retired During Period, Shares		369,900	0
Stock Repurchased and Retired During Period, Value			13.3
Prior Periods
Equity, Class of Treasury Stock [Line Items]
Stock Repurchased and Retired During Period, Shares			89,569
Stock Repurchased and Retired During Period, Value			1.3
Share Repurchase Plan | Common Stock
Equity, Class of Treasury Stock [Line Items]
Common stock share purchase, reduction			0.1
Share Repurchase Plan | Additional Paid-in Capital
Equity, Class of Treasury Stock [Line Items]
Common stock share purchase, reduction			2.2
Share Repurchase Plan | Retained Earnings
Equity, Class of Treasury Stock [Line Items]
Common stock share purchase, reduction			$ 12.3