SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Computation of Basic and Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Accounting Policies [Abstract]
Net Income, Basic	$ 95,526	[1]	$ 51,711	[1]	$ 59,466	[1]	$ 65,468	[1]	$ 72,928	[1]	$ 75,285	[1]	$ 70,611	[1]	$ 52,850	[1]	$ 272,171	$ 271,674	$ 256,996
Shares, Basic																	65,267,000	64,754,000	64,391,000
Per Share Amount, Basic	$ 1.46	[1]	$ 0.79	[1]	$ 0.91	[1]	$ 1.01	[1]	$ 1.13	[1]	$ 1.16	[1]	$ 1.09	[1]	$ 0.82	[1]	$ 4.17	$ 4.20	$ 3.99
Effect of dilutive securities: Stock options, Shares																	514,000	649,000	637,000
Effect of dilutive securities: Stock options, Per Share Amount																	$ (0.03)	$ (0.05)	$ (0.04)
Net Income, Diluted																	$ 272,171	$ 271,674	$ 256,996
Shares, Diluted																	65,781,000	65,403,000	65,028,000
Per Share Amount, Diluted, Total	$ 1.45	[1]	$ 0.79	[1]	$ 0.90	[1]	$ 1.00	[1]	$ 1.12	[1]	$ 1.15	[1]	$ 1.08	[1]	$ 0.81	[1]	$ 4.14	$ 4.15	$ 3.95
Outstanding stock options excluded in the calculation of earnings per share																	656,000	664,000	500,000

[1] The sum of the individual quarterly net income per common share amounts may not agree with year-to-date net income per common share as each quarterly computation is based on the weighted average number of common shares outstanding during that period.