CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 315,075	$ 289,817	$ 243,194
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on sale of discontinued operations	0	0	(8,203)
Depreciation and amortization:
Charged to depreciation and amortization	274,796	253,987	236,928
Charged to other accounts	1,209	969	679
Deferred income taxes	192,886	189,952	141,336
Stock-based compensation	27,491	25,531	17,814
Debt financing costs	5,922	9,409	8,480
Other	(850)	(428)	(2,887)
Changes in assets and liabilities:
(Increase) decreased in accounts receivable	48,240	(41,408)	(73,669)
Decrease in gas stored underground	33,234	(31,996)	31,979
(Increase) decrease in other current assets	(11,951)	(24,411)	15,644
(Increase) decrease in deferred charges and other assets	58,256	30,662	111,069
Increase (decrease) in account payable and accrued liabilities	(52,660)	55,041	31,912
Increase (decrease) in other current liabilities	896	2,413	(44,491)
Increase (decrease) in deferred credits and other liabilities	(56,025)	(19,552)	(96,658)
Net cash provided by operating activities	836,519	739,986	613,127
CASH FLOWS USED IN INVESTING ACTIVITIES
Capital expenditures	(975,132)	(835,251)	(845,033)
Proceeds from the sale of discontinued operations	0	0	153,023
Other, net	377	(2,325)	(4,904)
Net cash used in investing activities	(974,755)	(837,576)	(696,914)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in short-term debt	254,780	(165,865)	(208,070)
Net proceeds from issuance of long-term debt	493,538	0	493,793
Net proceeds from equity offering	0	390,205	0
Settlement of Treasury lock agreement	13,364	0	(66,626)
Repayment of long-term debt	(500,000)	0	(131)
Cash dividends paid	(160,018)	(146,248)	(128,115)
Repurchase of equity awards	(7,985)	(8,717)	(5,150)
Issuance of common stock	30,952	4,274	46
Net cash provided by (used in) financing activities	124,631	73,649	85,747
Net increase (decrease) in cash and cash equivalents	(13,605)	(23,941)	1,960
Cash and cash equivalents at beginning of period	42,258	66,199	64,239
Cash and cash equivalents at end of period	28,653	42,258	66,199
CASH PAID (RECEIVED) DURING THE PERIOD FOR:
Interest	151,334	156,606	148,461
Income taxes	$ 1,802	$ (610)	$ 10,008