Statement of Financial Position (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Mar. 31, 2012
Current assets:
Accounts receivable allowance for doubtful accounts	$ 3,023	$ 2,473
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	37,861,622	37,805,697
Common stock, shares outstanding	31,197,704	31,323,538
Treasury stock, shares	6,663,918	6,482,159