Net Sales and Operating Income of Acquired Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Operating Income	$ 69,543	$ 41,305	$ 124,608	$ 70,400
Recently Acquired Assets [Member]
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net Sales	52,603		93,683
Operating Income	$ 12,288		$ 18,713