CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
ASSETS
Property, plant and equipment	$ 7,435,103	$ 7,134,470
Less accumulated depreciation and amortization	1,724,830	1,658,866
Net property, plant and equipment	5,710,273	5,475,604
Current assets
Cash and cash equivalents	65,547	64,239
Accounts receivable, net	485,601	234,526
Gas stored underground	197,356	256,415
Other current assets	253,916	272,782
Total current assets	1,002,420	827,962
Goodwill and intangible assets	740,825	740,847
Deferred charges and other assets	500,212	451,262
Total assets	7,953,730	7,495,675
Shareholders' equity
Common stock, no par value (stated at $.005 per share)	453	451
Additional paid-in capital	1,753,024	1,745,467
Retained earnings	793,927	660,932
Accumulated other comprehensive income (loss)	(3,934)	(47,607)
Shareholders' equity	2,543,470	2,359,243
Long-term debt	2,455,514	1,956,305
Total capitalization	4,998,984	4,315,548
Current liabilities
Accounts payable and accrued liabilities	316,411	215,229
Other current liabilities	377,357	489,665
Short-term debt	232,998	570,929
Current maturities of long-term debt	0	131
Total current liabilities	926,766	1,275,954
Deferred income taxes	1,168,140	1,015,083
Regulatory cost of removal obligation	366,854	381,164
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	453,548	457,196
Deferred credits and other liabilities	39,438	50,730
Total shareholders' equity and liabilities	$ 7,953,730	$ 7,495,675