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, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Earnings Per Share [Abstract]
Net income	$ 27,943	$ 34,383	$ 23,138	$ 26,953	$ 28,709	$ 28,206	[1]	$ 25,924	$ 23,563	$ 112,417	$ 106,402	$ 109,036
Earnings Per Share, Basic and Diluted [Abstract]
Weighted average common shares-basic										42,452	41,748	44,023
Dilutive effect of employee equity incentive plans										912	990	1,242
Weighted average common shares-diluted										43,364	42,738	45,265
Basic net income per common share (in dollars per share)	$ 0.67	$ 0.81	$ 0.54	$ 0.63	$ 0.68	$ 0.68	[1]	$ 0.62	$ 0.57	$ 2.65	$ 2.55	$ 2.48
Diluted net income per common share (in dollars per share)	$ 0.65	$ 0.80	$ 0.53	$ 0.62	$ 0.67	$ 0.66	[1]	$ 0.61	$ 0.55	$ 2.59	$ 2.49	$ 2.41
Potentially dilutive securities excluded from diluted earnings per share because their effect is anti-dilutive										202	1,038	1,199

[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.