COMPREHENSIVE INCOME, DIVIDENDS, SHARE REPURCHASES AND EARNINGS PER SHARE (Details) (USD $)	1 Months Ended	3 Months Ended			6 Months Ended
	Nov. 30, 2011	Sep. 30, 2011	Jun. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Comprehensive Income (Loss), Net of Tax, Dividends, Share Repurchases and Earnings Per Share [Abstract]
Net income		$ 2,961,000		$ 38,848,000	$ 24,180,000	$ 59,756,000
Currency translation adjustments		(12,145,000)		19,815,000	(11,360,000)	9,828,000
Unrealized gain (loss) on cash flow hedges, net		(1,653,000)		860,000	(2,150,000)	860,000
Comprehensive income		(10,837,000)		59,523,000	10,670,000	70,444,000
Dividends paid		5,400,000	5,400,000
Cash dividends declared per common share		$ 0.15		$ 0.00	$ 0.30	$ 0.00
Stock repurchase authorized amount	100,000,000
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Income available to common stockholders - basic		2,711,000		38,880,000	23,756,000	59,688,000
Interest expense on assumed conversion of 3% Convertible Notes, net of tax		0		0	0	0
Income available to common stockholders - diluted		$ 2,711,000		$ 38,880,000	$ 23,756,000	$ 59,688,000
Weighted average number of common shares outstanding - basic		36,157,917		36,174,615	36,165,247	35,975,141
Assumed conversion of 3% Convertible Senior Noted outstanding during the period		0		0	0	0
Net effect of dilutive stock options, restricted stock units and restricted stock awards based on the treasury stock method		614,191		546,758	659,893	550,682
Weighted average number of common shares outstanding - diluted		36,772,108		36,721,373	36,825,140	36,525,823
Basic earnings per share		$ 0.07		$ 1.07	$ 0.66	$ 1.66
Diluted earnings per share		$ 0.07		$ 1.06	$ 0.65	$ 1.63
Earnings Per Share Potentially Dilutive Securities		1.5 million		1.5 million	1.5 million	1.5 million
Debt Instrument Convertible Terms Of Conversion Feature					The initial base conversion price of the notes is approximately $77.34 (subject to adjustment in certain circumstances), based on the initial base conversion rate of 12.9307 shares of Common Stock per $1,000 principal amount of convertible notes. In general, upon conversion of a note, the holder will receive cash equal to the principal amount of the note and Common Stock to the extent of the note’s conversion value in excess of such principal amount. In addition, if at the time of conversion the applicable price of our Common Stock exceeds the base conversion price, holders will receive up to an additional 8.4049 shares of our Common Stock per $1,000 principal amount of notes, as determined pursuant to a specified formula.
Debt Instrument, Convertible, Conversion Price		$ 77.34		$ 77.34	$ 77.34	$ 77.34
Quarter To Date [Member] | Stock Options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding		528,501		544,615
Weighted average exercise price		$ 36.85		$ 31.49	$ 36.85	$ 31.49
Year To Date [Member] | Stock Options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding					531,679	437,122
Weighted average exercise price		$ 36.81		$ 32.90	$ 36.81	$ 32.90
Quarter To Date [Member] | Restricted Stock Units [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding		83,925		213,980
Weighted average exercise price		$ 46.70		$ 40.08	$ 46.70	$ 40.08
Year To Date [Member] | Restricted Stock Units [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding					83,937	219,651
Weighted average exercise price		$ 46.70		$ 40.02	$ 46.70	$ 40.02
Quarter To Date [Member] | Restricted Stock Awards [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding		0		0
Weighted average exercise price		$ 0.00		$ 0.00	$ 0.00	$ 0.00
Year To Date [Member] | Restricted Stock Awards [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding					0	0
Weighted average exercise price		$ 0.00		$ 0.00	$ 0.00	$ 0.00