CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 289,817	$ 243,194	$ 216,717
Adjustments to reconcile net income to net cash provided by operating activities:
Asset impairments	0	0	5,288
Gain on sale of discontinued operations	0	(8,203)	(9,868)
Depreciation and amortization:
Charged to depreciation and amortization	253,987	236,928	246,093
Charged to other accounts	969	679	484
Deferred income taxes	189,952	141,336	104,319
Stock-based compensation	25,531	17,814	19,222
Debt financing costs	9,409	8,480	8,147
Other	(428)	(2,887)	(493)
Changes in assets and liabilities:
(Increase) decreased in accounts receivable	(41,408)	(73,669)	32,578
Decrease in gas stored underground	(31,996)	31,979	28,417
(Increase) decrease in other current assets	(24,411)	15,644	20,989
(Increase) decrease in deferred charges and other assets	30,662	111,069	(50,055)
Increase (decrease) in account payable and accrued liabilities	55,041	31,912	(64,234)
Increase (decrease) in other current liabilities	2,413	(44,491)	7,889
Increase (decrease) in deferred credits and other liabilities	(19,552)	(96,658)	21,424
Net cash provided by operating activities	739,986	613,127	586,917
CASH FLOWS USED IN INVESTING ACTIVITIES
Capital expenditures	(835,251)	(845,033)	(732,858)
Proceeds from the sale of discontinued operations	0	153,023	128,223
Other, net	(2,325)	(4,904)	(4,625)
Net cash used in investing activities	(837,576)	(696,914)	(609,260)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in short-term debt	(165,865)	(208,070)	354,141
Net proceeds from issuance of long-term debt	0	493,793	0
Net proceeds from equity offering	390,205	0	0
Settlement of Treasury lock agreement	0	(66,626)	0
Repayment of long-term debt	0	(131)	(257,034)
Cash dividends paid	(146,248)	(128,115)	(125,796)
Repurchase of common stock	0	0	(12,535)
Repurchase of equity awards	(8,717)	(5,150)	(5,219)
Issuance of common stock	4,274	46	1,606
Net cash provided by (used in) financing activities	73,649	85,747	(44,837)
Net increase (decrease) in cash and cash equivalents	(23,941)	1,960	(67,180)
Cash and cash equivalents at beginning of period	66,199	64,239	131,419
Cash and cash equivalents at end of period	42,258	66,199	64,239
CASH PAID (RECEIVED) DURING THE PERIOD FOR:
Interest	156,606	148,461	150,606
Income taxes	$ (610)	$ 10,008	$ (432)