COMPUTATION OF EARNINGS PER COMMON SHARE (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended									12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2011
Earnings Per Share [Abstract]
Net income	$ 28,709	$ 28,206	[1]	$ 25,924	$ 23,563	$ 23,886	$ 30,898	$ 27,521	$ 26,731	$ 106,402	$ 109,036	$ 109,243
Earnings Per Share, Basic and Diluted [Abstract]
Weighted average common shares-basic										41,748	44,023	47,713
Dilutive effect of employee equity incentive plans										990	1,242	1,631
Weighted average common shares-diluted										42,738	45,265	49,344
Earnings per Common Share - Basic	$ 0.68	$ 0.68	[1]	$ 0.62	$ 0.57	$ 0.57	$ 0.73	$ 0.62	$ 0.57	$ 2.55	$ 2.48	$ 2.29
Earnings per Common Share - Diluted	$ 0.67	$ 0.66	[1]	$ 0.61	$ 0.55	$ 0.55	$ 0.71	$ 0.60	$ 0.56	$ 2.49	$ 2.41	$ 2.21
Potentially dilutive securities excluded from earnings per common share-diluted because their effect is anti-dilutive										1,038	1,199	1,606

[1] We initiated a restructuring plan during the third quarter of fiscal year 2013. Under the plan, we eliminated certain positions in the US., Mexico, China, and Europe, and transitioned some of these positions to lower cost locations. The pre-tax charges incurred during fiscal year 2013 included $1.9 million for severance and related benefits and an immaterial amount of accelerated amortization on leasehold assets with no alternative future use.