CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012
ASSETS
Property, plant and equipment	$ 7,494,175	$ 7,134,470
Less accumulated depreciation and amortization	1,652,960	1,658,866
Net property, plant and equipment	5,841,215	5,475,604
Current assets
Cash and cash equivalents	31,979	64,239
Accounts receivable, net	350,237	234,526
Gas stored underground	209,101	256,415
Other current assets	90,936	272,782
Total current assets	682,253	827,962
Goodwill and intangible assets	740,814	740,847
Deferred charges and other assets	538,516	451,262
Total assets	7,802,798	7,495,675
Shareholders' equity
Common stock, no par value (stated at $.005 per share)	453	451
Additional paid-in capital	1,757,059	1,745,467
Retained earnings	800,643	660,932
Accumulated other comprehensive income (loss)	23,289	(47,607)
Shareholders' equity	2,581,444	2,359,243
Long-term debt	2,455,593	1,956,305
Total capitalization	5,037,037	4,315,548
Current liabilities
Accounts payable and accrued liabilities	229,876	215,229
Other current liabilities	348,706	489,665
Short-term debt	141,998	570,929
Current maturities of long-term debt	0	131
Total current liabilities	720,580	1,275,954
Deferred income taxes	1,197,274	1,015,083
Regulatory cost of removal obligation	360,578	381,164
Pension and postretirement liabilities	444,540	457,196
Deferred credits and other liabilities	42,789	50,730
Total shareholders' equity and liabilities	$ 7,802,798	$ 7,495,675