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, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Net Income
Basic earnings per share	$ 101,893	[1]	$ 89,981	[1]	$ 85,519	[1]	$ 72,831	[1]	$ 95,526	[1]	$ 51,711	[1]	$ 59,466	[1]	$ 65,468	[1]	$ 350,224	$ 272,171	$ 271,674
Stock options																	0	0	0
Restricted stock																	0	0	0
Diluted earnings per share																	$ 350,224	$ 272,171	$ 271,674
Shares
Basic earnings per share (in shares)																	65,073,000	65,267,000	64,754,000
Stock options (in shares)																	354,000	255,000	245,000
Restricted stock (in shares)																	418,000	259,000	404,000
Diluted earnings per share (in shares)																	65,845,000	65,781,000	65,403,000
Per Share Amount
Basic earnings per share (in dollars per share)	$ 1.59	[1]	$ 1.38	[1]	$ 1.30	[1]	$ 1.11	[1]	$ 1.46	[1]	$ 0.79	[1]	$ 0.91	[1]	$ 1.01	[1]	$ 5.38	$ 4.17	$ 4.20
Stock options (in dollars per share)																	$ (0.03)	$ (0.01)	$ (0.02)
Restricted stock (in dollars per share)																	$ (0.03)	$ (0.02)	$ (0.03)
Diluted earnings per share (in dollars per share)	$ 1.57	[1]	$ 1.37	[1]	$ 1.28	[1]	$ 1.10	[1]	$ 1.45	[1]	$ 0.79	[1]	$ 0.90	[1]	$ 1.00	[1]	$ 5.32	$ 4.14	$ 4.15
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding stock options excluded in the calculation of earnings per share																	0	656,000	664,000

[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.