SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) (USD $)	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
SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)
Revenues	$ 864,536,000	$ 840,197,000	$ 838,309,000	$ 844,572,000	$ 829,447,000	$ 819,785,000	$ 769,982,000	$ 732,588,000	$ 3,387,614,000	$ 3,151,802,000	$ 2,543,894,000
Operating income	243,234,000	239,960,000	232,920,000	240,547,000	239,380,000	232,655,000	207,025,000	230,539,000	956,661,000	909,599,000	702,511,000
Income from continuing operations	159,797,000	250,978,000	151,067,000	159,611,000	149,606,000	149,943,000	129,763,000	144,297,000	721,453,000	573,609,000	434,668,000
Net income	159,797,000	266,159,000	151,080,000	159,603,000	157,115,000	149,925,000	129,719,000	144,286,000	736,639,000	581,045,000	434,186,000
Basic earnings per common share:
Income from continuing operations (in dollars per share)	$ 1.49	$ 2.35	$ 1.41	$ 1.50	$ 1.41	$ 1.40	$ 1.20	$ 1.34	$ 6.75	$ 5.35	$ 4.06
Net income (in dollars per share)	$ 1.49	$ 2.49	$ 1.41	$ 1.50	$ 1.48	$ 1.40	$ 1.20	$ 1.34	$ 6.89	$ 5.42	$ 4.06
Diluted earnings per common share:
Income from continuing operations (in dollars per share)	$ 1.47	$ 2.32	$ 1.39	$ 1.48	$ 1.39	$ 1.38	$ 1.18	$ 1.32	$ 6.65	$ 5.27	$ 3.99
Net income (in dollars per share)	$ 1.47	$ 2.46	$ 1.39	$ 1.48	$ 1.46	$ 1.38	$ 1.18	$ 1.32	$ 6.79	$ 5.34	$ 3.99
Gain from the sale of assets, net	2,800,000	2,600,000	3,400,000	3,400,000	3,000,000	1,300,000	4,900,000	3,000,000
Gain from the sale of assets, per diluted share (in dollars per share)	$ 0.03	$ 0.02	$ 0.03	$ 0.03	$ 0.03	$ 0.01	$ 0.05	$ 0.03
Gain on sale of investment securities		$ 92,400,000		$ 5,500,000					$ 162,121,000		$ 913,000
Gain from the sale of investment securities, per diluted share (in dollars per share)		$ 0.86		$ 0.05