CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 176,763	$ 166,390
Adjustments to reconcile net income to cash flows from operating activities:
Unrealized (gain) loss on derivative instruments	(19,010)	45,810
Depreciation and amortization	45,164	39,014
Allowance for equity used during construction	(3,371)	(1,154)
Allowance for bad debt expense	2,143	1,685
Deferred income taxes	36,764	21,226
Manufactured gas plant remediation costs	(4,745)	(3,391)
Equity in earnings of equity investees, net of distributions received	3,909	1,364
Cost of removal - asset retirement obligations	(467)	(257)
Contributions to postemployment benefit plans	(2,466)	(3,618)
Changes in:
Components of working capital	88,290	83,223
Other noncurrent assets	22,572	15,735
Other noncurrent liabilities	34,214	10,434
Cash flows from operating activities	379,760	376,461
CASH FLOWS (USED IN) INVESTING ACTIVITIES
Utility plant expenditures	(96,626)	(90,381)
Solar and wind equipment expenditures	(111,588)	(91,569)
Real estate properties and other expenditures	(90)	(636)
Cost of removal expenditures	(19,114)	(18,690)
Investments in equity investees	(2,313)	0
Distribution from equity investees in excess of equity in earnings	2,269	1,344
Proceeds from sale of asset	0	6,010
(Payment to) withdrawal from restricted cash construction fund	(1,484)	100
Cash flows (used in) investing activities	(228,946)	(193,822)
CASH FLOWS (USED IN) FINANCING ACTIVITIES
Proceeds from issuance of common stock	33,659	12,161
Tax benefit from stock options exercised	838	348
Proceeds from sale-leaseback transaction	7,216	7,576
Proceeds from long-term debt	250,000	125,000
Payments of long-term debt	(7,227)	(78,964)
Purchases of treasury stock	(9,045)	(4,387)
Payments of common stock dividends	(57,226)	(52,922)
Net payments of short-term debt	(301,000)	(191,100)
Cash flows (used in) financing activities	(82,785)	(182,288)
Change in cash and cash equivalents	68,029	351
Cash and cash equivalents at beginning of period	2,151	2,969
Cash and cash equivalents at end of period	70,180	3,320
CHANGES IN COMPONENTS OF WORKING CAPITAL
Receivables	(8,566)	(37,575)
Inventories	160,809	100,021
Recovery of gas costs	18,109	(5,725)
Gas purchases payable	(47,371)	3,367
Gas purchases payable - related parties	50	0
Prepaid and accrued taxes	(5,063)	28,404
Accounts payable and other	(26,829)	8,439
Restricted broker margin accounts	3,466	(19,045)
Customers' credit balances and deposits	(5,784)	(4,738)
Other current assets	(531)	10,075
Components of working capital	88,290	83,223
SUPPLEMENTAL DISCLOSURES OF CASH FLOWS INFORMATION
Cash paid for Interest (net of amounts capitalized)	14,324	12,419
Cash paid for Income taxes	22,818	12,782
SUPPLEMENTAL SCHEDULE OF NONCASH INVESTING ACTIVITIES
Accrued capital expenditures	$ 30,038	$ 14,317