Treasury Stock - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended				9 Months Ended		135 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Jul. 26, 2006	Sep. 17, 2001	Dec. 31, 2012 Restricted Stock Units	Dec. 31, 2012 Open Market Stock Repurchase Program	Dec. 31, 2012 Open Market Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock authorized to repurchase under stock repurchase program			4,000,000	1,000,000
Additional stock authorized to repurchase under stock repurchase program			3,000,000
Shares repurchased during the period, shares					161,327	749,499	2,506,293
Shares repurchased during the period, value	$ 20,727	$ 17,939			$ 3,700	$ 17,000