CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
OPERATING REVENUES
Utility	$ 310,167	$ 297,220	$ 505,896	$ 516,843
Nonutility	492,020	342,394	750,596	737,807
Total operating revenues	802,187	639,614	1,256,492	1,254,650
Natural gas purchases:
Gas purchases - Related parties	1,730	1,506	3,464	3,030
Operation and maintenance	110,265	66,832	183,901	130,177
Regulatory rider expenses	18,413	15,330	29,114	27,072
Depreciation and amortization	26,848	27,516	54,210	52,153
Total operating expenses	600,979	541,131	943,804	1,051,549
OPERATING INCOME	201,208	98,483	312,688	203,101
Other income, net	5,007	7,261	9,124	7,547
Interest expense, net of capitalized interest	20,153	19,203	39,939	35,273
INCOME BEFORE INCOME TAXES AND EQUITY IN EARNINGS OF AFFILIATES	186,062	86,541	281,873	175,375
Income tax provision	39,057	16,284	56,498	32,755
Equity in earnings of affiliates	2,804	3,589	5,479	6,978
NET INCOME	$ 149,809	$ 73,846	$ 230,854	$ 149,598
EARNINGS PER COMMON SHARE
Basic (usd per share)	$ 1.56	$ 0.78	$ 2.40	$ 1.60
Diluted (usd per share)	$ 1.55	$ 0.77	$ 2.39	$ 1.59
WEIGHTED AVERAGE SHARES OUTSTANDING
Basic (in shares)	96,248	95,584	96,181	93,747
Diluted (in shares)	96,618	95,890	96,598	94,073
Regulated
Natural gas purchases:
Gas purchases - Utility and Nonutility	$ 113,235	$ 111,563	$ 169,380	$ 203,377
Unregulated
Natural gas purchases:
Gas purchases - Utility and Nonutility	$ 330,488	$ 318,384	$ 503,735	$ 635,740