Summarized Financial Information for Joint Venture Unconsolidated (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	Mar. 31, 2013
Segment Reporting Information [Line Items]
Current Assets	$ 300,705		$ 300,705		$ 261,271
Current Liabilities	101,691		101,691		100,229
Joint Venture [Member]
Segment Reporting Information [Line Items]
Revenues	54,756	48,057	111,564	95,944
Gross Margin	20,641	18,580	37,335	32,489
Earnings Before Income Taxes	19,649	17,501	35,568	30,437
Current Assets	52,548		52,548		53,059
Non-Current Assets	42,691		42,691		44,120
Current Liabilities	$ 18,631		$ 18,631		$ 12,913