Consolidated Statements Of Income And Earnings Reinvested In The Business (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
INCOME
Operating Revenues	$ 546,557	$ 441,160
Operating Expenses:
Purchased Gas	101,628	51,620
Property, Franchise and Other Taxes	24,501	22,781
Depreciation, Depletion and Amortization	88,578	83,120
Impairment of Oil and Gas Producing Properties	0	76,152
Total Operating Expenses	336,898	348,684
Gain on Sale of Timber Properties	0	51,066
Operating Income	209,659	143,542
Other Income (Expense):
Other Income (Deductions)	(1,079)	(2,176)
Interest Expense on Long-Term Debt	(30,130)	(32,256)
Other Interest Expense	(1,161)	(1,919)
Income Before Income Taxes	177,289	107,191
Income Tax Expense	44,897	29,417
Net Income Available for Common Stock	132,392	77,774
EARNINGS REINVESTED IN THE BUSINESS
Balance at Beginning of Period	1,191,175	991,630
Beginning Retained Earnings Unappropriated And Current Period Net Income	1,323,567	1,069,404
Dividends on Common Stock	(41,604)	(40,560)
Balance at December 31	$ 1,281,963	$ 1,028,844
Earnings Per Common Share, Basic:
Net Income Available for Common Stock (in dollars per share)	$ 1.45	$ 0.85
Earnings Per Common Share, Diluted:
Net Income Available for Common Stock (in dollars per share)	$ 1.44	$ 0.85
Weighted Average Common Shares Outstanding:
Used in Basic Calculation (shares)	91,266,300	91,007,657
Used in Diluted Calculation (shares)	92,032,775	91,508,259
Dividends Per Common Share:
Dividends Declared (in dollars per share)	$ 0.455	$ 0.445
Utility and Energy Marketing [Member]
INCOME
Operating Revenues	$ 236,684	$ 189,466
Operating Expenses:
Operation and Maintenance	46,644	44,886
Exploration and Production and Other [Member]
INCOME
Operating Revenues	244,281	192,035
Operating Expenses:
Operation and Maintenance	45,619	42,027
Pipeline and Storage and Gathering [Member]
INCOME
Operating Revenues	65,592	59,659
Operating Expenses:
Operation and Maintenance	$ 29,928	$ 28,098