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, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Net Income
Basic earnings per share	$ 112,200	[1]	$ 71,925	[1]	$ 73,300	[1]	$ 83,397	[1]	$ 101,893	[1]	$ 89,981	[1]	$ 85,519	[1]	$ 72,831	[1]	$ 340,822	$ 350,224	$ 272,171
Stock options																	0	0	0
Restricted stock																	0	0	0
Diluted earnings per share																	$ 340,822	$ 350,224	$ 272,171
Shares
Basic earnings per share (in shares)																	64,240,000	65,073,000	65,267,000
Stock options (in shares)																	239,000	354,000	255,000
Restricted stock (in shares)																	595,000	418,000	259,000
Diluted earnings per share (in shares)																	65,074,000	65,845,000	65,781,000
Per Share Amount
Basic earnings per share (in dollars per share)	$ 1.74	[1]	$ 1.12	[1]	$ 1.14	[1]	$ 1.30	[1]	$ 1.59	[1]	$ 1.38	[1]	$ 1.30	[1]	$ 1.11	[1]	$ 5.31	$ 5.38	$ 4.17
Stock options (in dollars per share)																	$ (0.01)	$ (0.03)	$ (0.01)
Restricted stock (in dollars per share)																	$ (0.06)	$ (0.03)	$ (0.02)
Diluted earnings per share (in dollars per share)	$ 1.72	[1]	$ 1.11	[1]	$ 1.13	[1]	$ 1.28	[1]	$ 1.57	[1]	$ 1.37	[1]	$ 1.28	[1]	$ 1.10	[1]	$ 5.24	$ 5.32	$ 4.14
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	0	656,000

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