CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 243,194	$ 216,717	$ 207,601
Adjustments to reconcile net income to net cash provided by operating activities:
Asset impairments	0	5,288	30,270
Gain on sale of discontinued operations	(8,203)	(9,868)	0
Depreciation and amortization:
Charged to depreciation and amortization	236,928	246,093	233,155
Charged to other accounts	679	484	228
Deferred income taxes	141,336	104,319	117,353
Stock-based compensation	17,814	19,222	11,586
Debt financing costs	8,480	8,147	9,438
Other	(2,887)	(493)	(961)
Changes in assets and liabilities:
(Increase) decreased in accounts receivable	(73,669)	32,578	(96)
Decrease in gas stored underground	31,979	28,417	27,737
(Increase) decrease in other current assets	15,644	20,989	(38,048)
(Increase) decrease in deferred charges and other assets	111,069	(50,055)	(53,519)
Increase (decrease) in account payable and accrued liabilities	31,912	(64,234)	23,904
Increase (decrease) in other current liabilities	(44,491)	7,889	(57,495)
Increase (decrease) in deferred credits and other liabilities	(96,658)	21,424	71,691
Net cash provided by operating activities	613,127	586,917	582,844
CASH FLOWS USED IN INVESTING ACTIVITIES
Capital expenditures	(845,033)	(732,858)	(622,965)
Proceeds from the sale of discontinued operations	153,023	128,223	0
Other, net	(4,904)	(4,625)	(4,421)
Net cash used in investing activities	(696,914)	(609,260)	(627,386)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in short-term debt	(208,070)	354,141	83,306
Net proceeds from issuance of long-term debt	493,793	0	394,466
Settlement of Treasury lock agreement	(66,626)	0	20,079
Unwinding of Treasury lock agreements	0	0	27,803
Repayment of long-term debt	(131)	(257,034)	(360,131)
Cash dividends paid	(128,115)	(125,796)	(124,011)
Repurchase of common stock	0	(12,535)	0
Repurchase of equity awards	(5,150)	(5,219)	(5,299)
Issuance of common stock	46	1,606	7,796
Net cash provided by (used in) financing activities	85,747	(44,837)	44,009
Net increase (decrease) in cash and cash equivalents	1,960	(67,180)	(533)
Cash and cash equivalents at beginning of period	64,239	131,419	131,952
Cash and cash equivalents at end of period	66,199	64,239	131,419
CASH PAID (RECEIVED) DURING THE PERIOD FOR:
Interest	148,461	150,606	157,976
Income taxes	$ 10,008	$ (432)	$ (8,329)