Statement of Financial Position (Parentheticals) (USD $)	Sep. 30, 2011	Mar. 31, 2011
Current assets:
Accounts receivable allowance for doubtful accounts	$ 3,145,000	$ 3,478,000
Stockholders' equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	80,000,000	80,000,000
Common stock, shares issued	37,648,768	37,352,509
Common stock, shares outstanding	31,170,402	31,452,922
Treasury stock, shares	6,478,366	5,899,587