CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Operating revenues	$ 1,484,009	$ 1,012,786
Purchased gas cost	738,249	371,163
Operation and maintenance expense	185,016	159,110
Depreciation and amortization expense	146,020	127,856
Taxes, other than income	93,538	78,796
Operating income	321,186	275,861
Other non-operating income	21,191	8,702
Interest charges	36,760	19,851
Income before income taxes	305,617	264,712
Income tax expense	33,757	15,503
Net income	$ 271,860	$ 249,209
Basic net income per share (USD per share)	$ 1.92	$ 1.86
Diluted net income per share (USD per share)	1.91	1.86
Cash dividends (USD per share)	$ 0.74	$ 0.68
Basic weighted average shares outstanding (in shares)	141,820	133,682
Diluted weighted average shares outstanding (in shares)	141,937	133,689
Other comprehensive income (loss), net of tax
Net unrealized holding gains (losses) on available-for-sale securities, net of tax of $25 and $(20)	$ 87	$ (69)
Cash flow hedges:
Amortization and unrealized gains (losses) on interest rate agreements, net of tax of $6,397 and $(13,260)	22,131	(45,878)
Total other comprehensive income (loss)	22,218	(45,947)
Total comprehensive income	294,078	203,262
Distribution segment
Operating revenues	1,439,693	971,636
Pipeline and storage segment
Operating revenues	44,316	41,150
Purchased gas cost
Purchased gas cost	738,249	371,163
Operating Segments | Distribution segment
Operating revenues	1,440,426	972,422
Purchased gas cost	881,915	496,799
Operation and maintenance expense	136,469	123,284
Depreciation and amortization expense	105,664	92,797
Taxes, other than income	84,622	69,045
Operating income	231,756	190,497
Other non-operating income	6,774	1,916
Interest charges	22,839	8,548
Income before income taxes	215,691	183,865
Income tax expense	21,223	4,294
Net income	194,468	179,571
Operating Segments | Pipeline and storage segment
Operating revenues	186,629	162,918
Purchased gas cost	(858)	(3,411)
Operation and maintenance expense	48,785	36,155
Depreciation and amortization expense	40,356	35,059
Taxes, other than income	8,916	9,751
Operating income	89,430	85,364
Other non-operating income	14,417	6,786
Interest charges	13,921	11,303
Income before income taxes	89,926	80,847
Income tax expense	12,534	11,209
Net income	77,392	69,638
Operating Segments | Purchased gas cost | Distribution segment
Purchased gas cost	881,915	496,799
Operating Segments | Purchased gas cost | Pipeline and storage segment
Purchased gas cost	(858)	(3,411)
Eliminations
Operating revenues	(143,046)	(122,554)
Purchased gas cost	(142,808)	(122,225)
Operation and maintenance expense	(238)	(329)
Depreciation and amortization expense	0	0
Taxes, other than income	0	0
Operating income	0	0
Other non-operating income	0	0
Interest charges	0	0
Income before income taxes	0	0
Income tax expense	0	0
Net income	0	0
Eliminations | Distribution segment
Operating revenues	733	786
Eliminations | Pipeline and storage segment
Operating revenues	142,313	121,768
Eliminations | Purchased gas cost
Purchased gas cost	$ (142,808)	$ (122,225)