GUARANTOR AND NON-GUARANTOR FINANCIAL INFORMATION (Details 5) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	$ 1,418,744	$ 1,118,527	$ 997,185
INVESTING ACTIVITIES:
Capital expenditures	(1,133,482)	(952,892)	(809,066)
Purchase of short-term investments	(45,607)
Proceeds from asset sales	22,501	30,770	28,026
Proceeds from sale of investments		49,205	232,221
Net cash used in investing activities from continuing operations	(1,156,588)	(872,917)	(548,819)
Net cash provided by investing activities from discontinued operations			15,000
Net cash provided by (used in) investing activities	(1,156,588)	(872,917)	(533,819)
FINANCING ACTIVITIES:
Payments on long-term debt	(40,000)	(115,000)	(40,000)
Proceeds from senior notes, net of discount	497,125
Debt issuance costs	(5,474)
Proceeds on short-term debt	1,002
Payments on short-term debt	(1,002)
Repurchase of common stock	(59,654)
Dividends paid	(298,367)	(264,386)	(93,053)
Exercise of stock options, net of tax withholding	2,650	23,250	13,317
Tax withholdings related to net share settlements of restricted stock	(5,140)	(3,049)	(1,677)
Excess tax benefit from stock-based compensation	3,772	26,616	9,820
Net cash used in financing activities from continuing operations	94,912	(332,569)	(111,593)
Net increase (decrease) in cash and cash equivalents	357,068	(86,959)	351,773
Cash and cash equivalents, beginning of period	360,909	447,868	96,095
Cash and cash equivalents, end of period	717,977	360,909	447,868
Eliminations
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	(4,926)	(5,184)	2,561
FINANCING ACTIVITIES:
Net increase (decrease) in cash and cash equivalents	(4,926)	(5,184)	2,561
Cash and cash equivalents, beginning of period	(3,628)	1,556	(1,005)
Cash and cash equivalents, end of period	(8,554)	(3,628)	1,556
Guarantor/Parent | Reportable Legal Entities
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	3,623	(21,094)	3,066
INVESTING ACTIVITIES:
Capital expenditures	(24,818)	(17,786)	(6,828)
Intercompany transfers	24,818	17,786	6,828
Proceeds from asset sales	1	2	3,235
Net cash used in investing activities from continuing operations			3,235
Net cash provided by (used in) investing activities	1	2	3,235
FINANCING ACTIVITIES:
Intercompany transfers	358,021	264,386	93,053
Repurchase of common stock	(59,654)
Dividends paid	(298,367)	(264,386)	(93,053)
Intercompany notes			(16,500)
Exercise of stock options, net of tax withholding	2,650	23,250	13,317
Tax withholdings related to net share settlements of restricted stock	(5,140)	(3,049)	(1,677)
Excess tax benefit from stock-based compensation	78
Excess tax benefit from stock-based compensation		(957)	(563)
Net cash used in financing activities from continuing operations	(2,412)	19,244	(5,423)
Net increase (decrease) in cash and cash equivalents	1,212	(1,848)	878
Cash and cash equivalents, beginning of period	(2,050)	(202)	(1,080)
Cash and cash equivalents, end of period	(838)	(2,050)	(202)
Issuer Subsidiary | Reportable Legal Entities
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	1,379,707	1,050,609	973,850
INVESTING ACTIVITIES:
Capital expenditures	(1,064,288)	(840,341)	(752,642)
Purchase of short-term investments	(45,607)
Intercompany transfers	(24,818)	(17,786)	(6,828)
Proceeds from asset sales	21,329	27,401	21,694
Proceeds from sale of investments		49,205	232,221
Net cash used in investing activities from continuing operations			(505,555)
Net cash provided by (used in) investing activities	(1,113,384)	(781,521)	(505,555)
FINANCING ACTIVITIES:
Payments on long-term debt	(40,000)	(115,000)	(40,000)
Proceeds from senior notes, net of discount	497,125
Debt issuance costs	(5,474)
Intercompany transfers	(358,021)	(264,386)	(93,053)
Excess tax benefit from stock-based compensation	3,665	27,357	10,280
Net cash used in financing activities from continuing operations	97,295	(352,029)	(122,773)
Net increase (decrease) in cash and cash equivalents	363,618	(82,941)	345,522
Cash and cash equivalents, beginning of period	329,655	412,596	67,074
Cash and cash equivalents, end of period	693,273	329,655	412,596
Non-Guarantor Subsidiaries | Reportable Legal Entities
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS
Net cash provided by (used in) operating activities	40,340	94,196	17,708
INVESTING ACTIVITIES:
Capital expenditures	(44,376)	(94,765)	(49,596)
Proceeds from asset sales	1,171	3,367	3,097
Net cash used in investing activities from continuing operations			(46,499)
Net cash provided by investing activities from discontinued operations			15,000
Net cash provided by (used in) investing activities	(43,205)	(91,398)	(31,499)
FINANCING ACTIVITIES:
Proceeds on short-term debt	1,002
Payments on short-term debt	(1,002)
Intercompany notes			16,500
Excess tax benefit from stock-based compensation	29	216	103
Net cash used in financing activities from continuing operations	29	216	16,603
Net increase (decrease) in cash and cash equivalents	(2,836)	3,014	2,812
Cash and cash equivalents, beginning of period	36,932	33,918	31,106
Cash and cash equivalents, end of period	$ 34,096	$ 36,932	$ 33,918