CONSOLIDATED STATEMENT OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 111,892	$ 88,436
Adjustments to reconcile net income to cash flows from operating activities:
Unrealized (gain) loss on derivative instruments	(15,353)	58,049
Depreciation and amortization	20,039	17,369
Allowance for equity used during construction	(139)	(499)
Allowance for bad debt expense	1,586	2,572
Deferred income taxes	20,920	(6,374)
Manufactured gas plant remediation costs	(4,964)	(5,727)
Equity in earnings of affiliates, net of distributions received	3,852	(13)
Cost of removal - asset retirement obligations	(368)	(456)
Contributions to postemployment benefit plans	(22,982)	(8,068)
Changes in:
Components of working capital	(31,567)	9,862
Other noncurrent assets	11,690	16,234
Other noncurrent liabilities	10,018	9,624
Cash flows from operating activities	104,624	181,009
CASH FLOWS (USED IN) INVESTING ACTIVITIES
Utility plant expenditures	(42,380)	(43,581)
Solar equipment expenditures	(61,786)	(11,533)
Real estate properties and other expenditures	(459)	(367)
Cost of removal expenditures	(6,765)	(3,605)
Withdrawal from restricted cash construction fund	136	38
Cash flows (used in) investing activities	(111,254)	(59,048)
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES
Proceeds from issuance of common stock	7,164	7,297
Tax benefit from stock options exercised	222	347
Proceeds from sale-leaseback transaction	6,522	5,901
Payments of long-term debt	(3,371)	(23,919)
Purchases of treasury stock	(4,800)	(7,222)
Payments of common stock dividends	(30,695)	(28,917)
Net proceeds from short-term debt	31,950	0
Cash flows from (used in) financing activities	6,992	(46,513)
Change in cash and cash equivalents	362	75,448
Cash and temporary investments at beginning of period	7,440	943
Cash and temporary investments at end of period	7,802	76,391
CHANGES IN COMPONENTS OF WORKING CAPITAL
Receivables	19,773	(106,839)
Inventories	118,920	141,246
Recovery of gas costs	(21,177)	28,309
Gas purchases payable	(80,941)	(1,285)
Prepaid and accrued taxes	47,025	78,809
Accounts payable and other	(4,573)	(3,414)
Restricted broker margin accounts	(14,249)	(48,713)
Customers' credit balances and deposits	(82,321)	(77,917)
Other current assets	(14,024)	(334)
Components of working capital	(31,567)	9,862
SUPPLEMENTAL DISCLOSURES OF CASH FLOWS INFORMATION
Cash paid for Interest (net of amounts capitalized)	8,324	9,172
Cash paid for Income taxes	814	4,047
Accrued Capital Expenditures	$ 5,041	$ (3,472)