Net Income (Loss) per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share [Abstract]
Net income (A)	$ 17,389	$ 22,478	$ 15,448	$ 27,743
Weighted average outstanding shares of common stock (B)	33,934,383	37,154,446	35,099,660	38,167,304
Dilutive effect of employee stock options and restricted stock units	50,730	449,321	68,837	355,403
Common stock and potential dilutive common shares (C)	33,985,113	37,603,767	35,168,497	38,522,707
Net income per share:
Basic (in dollars per share)	$ 0.51	$ 0.60	$ 0.44	$ 0.73
Diluted (A/C) (in dollars per share)	$ 0.51	$ 0.60	$ 0.44	$ 0.72