CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating revenues
Total operating revenues	$ 485,738	$ 562,245	$ 2,458,165	$ 2,670,846
Cost of Revenue	31,326	130,886	845,167	1,124,763
Operation and maintenance expense	164,545	143,748	452,572	431,952
Depreciation and amortization expense	97,700	90,671	290,537	268,426
Taxes, other than income	69,965	72,620	213,546	208,400
Operating income	122,202	124,320	656,343	637,305
Other non-operating income (expense)	1,645	(3,330)	(1,846)	(8,054)
Interest charges	19,592	23,349	74,390	82,162
Income before income taxes	104,255	97,641	580,107	547,089
Income tax expense	23,789	26,448	127,107	(17,228)
Net income	$ 80,466	$ 71,193	$ 453,000	$ 564,317
Basic net income per share	$ 0.68	$ 0.64	$ 3.89	$ 5.09
Diluted net income per share	0.68	0.64	3.88	5.09
Cash dividends per share	$ 0.525	$ 0.485	$ 1.575	$ 1.455
Basic weighted average shares outstanding	118,075	111,851	116,485	110,707
Diluted weighted average shares outstanding	118,430	111,851	116,673	110,707
Other comprehensive income (loss), net of tax
Net unrealized holding gains (losses) on available-for-sale securities, net of tax	$ 94	$ 310	$ 191	$ (736)
Cash flow hedges:
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	1,053	8,320	(23,997)	29,609
Total other comprehensive income (loss)	1,147	8,630	(23,806)	28,873
Total comprehensive income	81,613	79,823	429,194	593,190
Operating Segments | Distribution segment
Operating revenues
Total operating revenues	444,944	535,488	2,341,668	2,595,571
Operation and maintenance expense	123,998	110,568	347,386	343,860
Depreciation and amortization expense	70,611	66,504	210,224	197,587
Taxes, other than income	62,134	64,420	189,377	184,219
Operating income	48,683	63,109	447,083	448,207
Other non-operating income (expense)	3,005	(2,518)	1,791	(5,961)
Interest charges	10,597	13,315	44,703	51,581
Income before income taxes	41,091	47,276	404,171	390,665
Income tax expense	8,693	11,932	85,195	(39,021)
Net income	32,398	35,344	318,976	429,686
Operating Segments | Pipeline and storage segment
Operating revenues
Total operating revenues	149,198	127,633	419,318	375,051
Operation and maintenance expense	40,855	33,494	106,120	89,027
Depreciation and amortization expense	27,089	24,167	80,313	70,839
Taxes, other than income	7,831	8,200	24,169	24,181
Operating income	73,519	61,211	209,260	189,098
Other non-operating income (expense)	(1,360)	(812)	(3,637)	(2,093)
Interest charges	8,995	10,034	29,687	30,581
Income before income taxes	63,164	50,365	175,936	156,424
Income tax expense	15,096	14,516	41,912	21,793
Net income	48,068	35,849	134,024	134,631
Intersegment eliminations
Operating revenues
Total operating revenues	(108,404)	(100,876)	(302,821)	(299,776)
Operation and maintenance expense	(308)	(314)	(934)	(935)
Depreciation and amortization expense	0	0	0	0
Taxes, other than income	0	0	0	0
Operating income	0	0	0	0
Other non-operating income (expense)	0	0	0	0
Interest charges	0	0	0	0
Income before income taxes	0	0	0	0
Income tax expense	0	0	0	0
Net income	0	0	0	0
Natural Gas, US Regulated
Operating revenues
Cost of Revenue	31,326	130,886	845,167	1,124,763
Natural Gas, US Regulated | Operating Segments | Distribution segment
Operating revenues
Cost of Revenue	139,518	230,887	1,147,598	1,421,698
Natural Gas, US Regulated | Operating Segments | Pipeline and storage segment
Operating revenues
Cost of Revenue	(96)	561	(544)	1,906
Natural Gas, US Regulated | Intersegment eliminations
Operating revenues
Cost of Revenue	$ (108,096)	$ (100,562)	$ (301,887)	$ (298,841)