Consolidated Statements of Income (USD $)	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Consolidated Statements of Income [Abstract]
Revenues	$ 412,668,000	$ 380,668,000	$ 337,968,000
Cost of revenues	318,826,000	284,098,000	252,429,000
Gross profit	93,842,000	96,570,000	85,539,000
General and administrative	50,405,000	59,167,000	42,056,000
Income before income taxes	43,437,000	37,403,000	43,483,000
Income tax provision	16,885,000	12,740,000	17,387,000
Net income	$ 26,552,000	$ 24,663,000	$ 26,096,000
Net income per share:
Basic	$ 2.31	$ 2.09	$ 2.09
Diluted	$ 2.28	$ 2.05	$ 2.06
Weighted average shares outstanding:
Basic	11,476,000	11,801,000	12,499,000
Diluted	11,627,000	12,029,000	12,672,000