DIVIDENDS, SHARE REPURCHASES AND EARNINGS PER SHARE (Details) (USD $)	3 Months Ended			6 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Dividends, Share Repurchases and Earnings Per Share [Line Items]
Cash dividends declared per common share	$ 0.20	$ 0.20	$ 0.15	$ 0.40	$ 0.30
Stock repurchase authorized amount	$ 100,000,000
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Income available to common stockholders - basic		29,668,000	2,711,000	53,330,000	23,756,000
Interest expense on assumed conversion of 3% Convertible Notes, net of tax		0	0	0	0
Income available to common stockholders - diluted		$ 29,668,000	$ 2,711,000	$ 53,330,000	$ 23,756,000
Basic earnings per share		$ 0.83	$ 0.07	$ 1.49	$ 0.66
Diluted earnings per share		$ 0.82	$ 0.07	$ 1.46	$ 0.65
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 base conversion price of the notes was approximately $75.65, based on the base conversion rate of 13.218 shares of Common Stock per $1,000 principal amount of convertible notes (subject to adjustment in certain circumstances, including the payment of dividends). 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 8.5916 shares of our Common Stock per $1,000 principal amount of notes, as determined pursuant to a specified formula.
Debt Instrument, Convertible, Conversion Price		$ 75.65		$ 75.65
Quarter To Date [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average number of common shares outstanding - basic		35,815,672	36,157,917
Assumed conversion of 3% Convertible Senior Noted outstanding during the period		0	0
Net effect of dilutive stock options, restricted stock units and restricted stock awards based on the treasury stock method		526,620	614,191
Weighted average number of common shares outstanding - diluted		36,342,292	36,772,108
Year To Date [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average number of common shares outstanding - basic				35,858,237	36,165,247
Assumed conversion of 3% Convertible Senior Noted outstanding during the period				0	0
Net effect of dilutive stock options, restricted stock units and restricted stock awards based on the treasury stock method				601,940	659,893
Weighted average number of common shares outstanding - diluted				36,460,177	36,825,140
Stock Options [Member] | Quarter To Date [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding		552,209	528,501
Weighted average exercise price		$ 43.56	$ 36.85	$ 43.56	$ 36.85
Stock Options [Member] | Year To Date [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding				448,269	531,679
Weighted average exercise price		$ 43.81	$ 36.81	$ 43.81	$ 36.81
Restricted Stock Units [Member] | Quarter To Date [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding		4,040	83,925
Weighted average exercise price		$ 53.89	$ 46.70	$ 53.89	$ 46.70
Restricted Stock Units [Member] | Year To Date [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Outstanding				58,016	83,937
Weighted average exercise price		$ 46.97	$ 46.70	$ 46.97	$ 46.70
Restricted Stock Awards [Member] | Quarter To Date [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
Restricted Stock Awards [Member] | Year To Date [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