Segment Information (Tables)

6 Months Ended

Mar. 31, 2016

Segment Reporting [Abstract]

Schedule of Segment Information

Financial information by business segment follows:

Three Months Ended March 31, 2016:

			Reportable Segments
	Total		Gas Utility		Electric Utility
Revenues	$	322,047	$	298,088	$	23,959
Cost of sales	$	137,434	$	123,702	$	13,732
Depreciation and amortization	$	17,030	$	15,822	$	1,208
Operating income	$	114,481	$	111,004	$	3,477
Interest expense	$	9,270	$	8,847	$	423
Income before income taxes	$	105,211	$	102,157	$	3,054
Capital expenditures (including the effects of accruals)	$	48,113	$	46,003	$	2,110

Three Months Ended March 31, 2015:

			Reportable Segments
	Total		Gas Utility		Electric Utility		Other
Revenues	$	500,573	$	468,000	$	32,323	$	250
Cost of sales	$	278,336	$	258,155	$	20,181	$	—
Depreciation and amortization	$	15,644	$	14,489	$	1,155	$	—
Operating income (loss)	$	142,699	$	139,303	$	3,510	$	(114	)
Interest expense	$	10,611	$	10,104	$	507	$	—
Income (loss) before income taxes	$	132,088	$	129,199	$	3,003	$	(114	)
Capital expenditures (including the effects of accruals)	$	41,280	$	39,202	$	2,078	$	—

Six Months Ended March 31, 2016:

			Reportable Segments
	Total		Gas Utility		Electric Utility
Revenues	$	520,029	$	475,030	$	44,999
Cost of sales	$	212,873	$	187,931	$	24,942
Depreciation and amortization	$	33,731	$	31,326	$	2,405
Operating income	$	162,777	$	156,824	$	5,953
Interest expense	$	18,764	$	17,913	$	851
Income before income taxes	$	144,013	$	138,911	$	5,102
Capital expenditures (including the effects of accruals)	$	109,577	$	105,273	$	4,304
As of March 31, 2016
Total assets (at period end)	$	2,641,587	$	2,488,191	$	153,396
Goodwill (at period end)	$	182,145	$	182,145	$	—

Six Months Ended March 31, 2015:

			Reportable Segments
	Total		Gas Utility		Electric Utility		Other
Revenues	$	787,879	$	728,478	$	58,746	$	655
Cost of sales	$	421,388	$	385,363	$	36,025	$	—
Depreciation and amortization	$	31,069	$	28,769	$	2,300	$	—
Operating income	$	218,339	$	211,149	$	7,229	$	(39	)
Interest expense	$	21,260	$	20,234	$	1,026	$	—
Income before income taxes	$	197,079	$	190,915	$	6,203	$	(39	)
Capital expenditures (including the effects of accruals)	$	96,309	$	92,694	$	3,615	$	—
As of March 31, 2015
Total assets (at period end)	$	2,506,043	$	2,359,060	$	146,983	$	—
Goodwill (at period end)	$	182,145	$	182,145	$	—	$	—