CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income	$ 601,443	$ 511,406	$ 603,064
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	429,828	391,456	361,083
Deferred income taxes	155,322	132,004	158,271
One-time income tax benefit	(20,962)	0	(158,782)
Stock-based compensation	9,583	11,121	12,863
Amortization of debt issuance costs	11,543	9,464	7,865
Equity component of AFUDC	(23,493)	(11,165)	0
Other	8,411	1,169	5,437
Changes in assets and liabilities:
(Increase) decrease in accounts receivable	7,167	18,724	(29,208)
Decrease in gas stored underground	18,188	35,594	18,921
(Increase) decrease in other current assets	(35,878)	(26,590)	60,424
Increase in deferred charges and other assets	(31,935)	(58,403)	(10,049)
Increase (decrease) in accounts payable and accrued liabilities	7,359	9,908	(11,857)
Increase (decrease) in other current liabilities	(129,543)	(103,895)	74,707
Increase in deferred credits and other liabilities	30,966	47,976	31,923
Net cash provided by operating activities	1,037,999	968,769	1,124,662
CASH FLOWS USED IN INVESTING ACTIVITIES
Capital expenditures	(1,935,676)	(1,693,477)	(1,467,591)
Proceeds from the sale of discontinued operations	0	4,000	3,000
Purchases of debt and equity securities	(50,517)	(29,153)	(46,401)
Proceeds from sale of debt and equity securities	32,339	6,070	22,360
Maturities of debt securities	18,669	20,299	15,716
Other, net	9,667	8,601	9,350
Net cash used in investing activities	(1,925,518)	(1,683,660)	(1,463,566)
CASH FLOWS FROM FINANCING ACTIVITIES
Net increase (decrease) in short-term debt	(464,915)	(110,865)	128,035
Proceeds from issuance of long-term debt, net of premium/discount	999,450	1,045,221	0
Net proceeds from equity offering	624,302	694,103	395,092
Issuance of common stock through stock purchase and employee retirement plans	19,548	19,323	19,563
Settlement of interest rate swaps	(4,426)	(90,141)	0
Repayment of long-term debt	0	(575,000)	0
Cash dividends paid	(282,444)	(245,717)	(214,906)
Debt issuance costs	(7,738)	(11,254)	0
Other	0	0	(1,518)
Net cash provided by financing activities	883,777	725,670	326,266
Net increase (decrease) in cash and cash equivalents	(3,742)	10,779	(12,638)
Cash and cash equivalents at beginning of year	24,550	13,771	26,409
Cash and cash equivalents at end of year	$ 20,808	$ 24,550	$ 13,771