Consolidated Statements Of Income And Earnings Reinvested In The Business (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
INCOME
Operating Revenues	$ 550,072	$ 452,854
Operating Expenses
Purchased Gas	167,605	121,919
Operation and Maintenance	107,846	107,732
Property, Franchise and Other Taxes	20,926	19,664
Depreciation, Depletion and Amortization	93,114	72,331
Total Operating Expenses	389,491	321,646
Operating Income	160,581	131,208
Other Income (Expense):
Interest Income	702	1,386
Other Income	228	1,415
Interest Expense on Long-Term Debt	(22,885)	(21,448)
Other Interest Expense	(949)	(1,068)
Income Before Income Taxes	137,677	111,493
Income Tax Expense	55,425	43,549
Net Income Available for Common Stock	82,252	67,944
EARNINGS REINVESTED IN THE BUSINESS
Balance at Beginning of Period	1,442,617	1,306,284
Beginning Retained Earnings Unappropriated And Current Period Net Income Loss	1,524,869	1,374,228
Dividends on Common Stock	(31,403)	(30,463)
Balance at December 31	$ 1,493,466	$ 1,343,765
Earnings Per Common Share, Basic:
Net Income Available for Common Stock	$ 0.98	$ 0.81
Earnings Per Common Share, Diluted:
Net Income Available for Common Stock	$ 0.97	$ 0.81
Weighted Average Common Shares Outstanding:
Used in Basic Calculation	83,707,687	83,390,278
Used in Diluted Calculation	84,659,001	84,006,050
Dividends Per Common Share:
Dividends Declared	$ 0.375	$ 0.365