Weighted Average Shares and Net Income Per Share (Details) (USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Calculations of the basic and diluted weighted shares
Net Income	$ 6,630,000	$ 7,881,000	$ 13,226,000	$ 16,079,000
Basic:
Weighted average common shares decreased	11,270,000	11,526,000	11,292,000	11,572,000
Net Income per share	$ 0.59	$ 0.68	$ 1.17	$ 1.39
Diluted:
Weighted average common shares outstanding	11,270,000	11,526,000	11,292,000	11,572,000
Treasury stock impact of stock options	106,000	146,000	109,000	157,000
Total common and common equivalent shares	11,376,000	11,672,000	11,401,000	11,729,000
Effect on diluted net income per share	$ 0.58	$ 0.68	$ 1.16	$ 1.37