CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Sep. 30, 2011
ASSETS
Property, plant and equipment	$ 6,992,899	$ 6,816,794
Less accumulated depreciation and amortization	1,658,887	1,668,876
Net property, plant and equipment	5,334,012	5,147,918
Current assets
Cash and cash equivalents	47,040	131,419
Accounts receivable, net	350,261	273,303
Gas stored underground	221,112	289,760
Other current assets	275,428	316,471
Total current assets	893,841	1,010,953
Goodwill and intangible assets	740,185	740,207
Deferred charges and other assets	400,689	383,793
Total assets	7,368,727	7,282,871
Shareholders' equity
Common stock, no par value (stated at $.005 per share)	450	451
Additional paid-in capital	1,728,150	1,732,935
Retained earnings	685,206	570,495
Accumulated other comprehensive income (loss)	(53,094)	(48,460)
Shareholders' equity	2,360,712	2,255,421
Long-term debt	1,956,213	2,206,117
Total capitalization	4,316,925	4,461,538
Current liabilities
Accounts payable and accrued liabilities	309,864	291,205
Other current liabilities	374,123	367,563
Short-term debt	173,996	206,396
Current maturities of long-term debt	250,131	2,434
Total current liabilities	1,108,114	867,598
Deferred income taxes	1,062,488	960,093
Regulatory cost of removal obligation	414,001	428,947
Deferred credits and other liabilities	467,199	564,695
Total shareholders' equity and liabilities	$ 7,368,727	$ 7,282,871