Consolidated Statements Of Income And Earnings Reinvested In The Business (Unaudited) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
INCOME
Operating Revenues	$ 523,909	$ 550,072
Operating Expenses
Purchased Gas	127,091	167,605
Operation and Maintenance	112,582	107,846
Property, Franchise and Other Taxes	20,929	20,926
Depreciation, Depletion and Amortization	102,747	93,114
Total Operating Expenses	363,349	389,491
Operating Income	160,560	160,581
Other Income (Expense):
Interest Income	1,258	702
Other Income	1,183	228
Interest Expense on Long-Term Debt	(22,311)	(22,885)
Other Interest Expense	(790)	(949)
Income Before Income Taxes	139,900	137,677
Income Tax Expense	55,160	55,425
Net Income Available for Common Stock	84,740	82,252
EARNINGS REINVESTED IN THE BUSINESS
Balance at Beginning of Period	1,614,361	1,442,617
Beginning Retained Earnings Unappropriated And Current Period Net Income Loss	1,699,101	1,524,869
Dividends on Common Stock	(32,442)	(31,403)
Balance at December 31	$ 1,666,659	$ 1,493,466
Earnings Per Common Share, Basic:
Net Income Available for Common Stock (in dollars per share)	$ 1.01	$ 0.98
Earnings Per Common Share, Diluted:
Net Income Available for Common Stock (in dollars per share)	$ 1.00	$ 0.97
Weighted Average Common Shares Outstanding:
Used in Basic Calculation (shares)	84,208,645	83,707,687
Used in Diluted Calculation (shares)	85,118,516	84,659,001
Dividends Per Common Share:
Dividends Declared (in dollars per share)	$ 0.385	$ 0.375