Segment Information (Tables)

9 Months Ended

Jun. 30, 2017

Segment Reporting [Abstract]

Schedule of Segment Information

Financial information by business segment follows:

			Reportable Segments
Three Months Ended June 30, 2017	Total		Gas Utility		Electric Utility
Revenues	$	146,692	$	127,849	$	18,843
Cost of sales — gas, fuel and purchased power	$	51,979	$	42,180	$	9,799
Depreciation and amortization	$	17,912	$	16,845	$	1,067
Operating income	$	27,671	$	25,628	$	2,043
Interest expense	$	10,128	$	9,601	$	527
Income before income taxes	$	17,543	$	16,027	$	1,516
Capital expenditures (including the effects of accruals)	$	79,088	$	75,836	$	3,252

			Reportable Segments
Three Months Ended June 30, 2016	Total		Gas Utility		Electric Utility
Revenues	$	140,283	$	119,995	$	20,288
Cost of sales — gas, fuel and purchased power	$	44,415	$	33,715	$	10,700
Depreciation and amortization	$	16,550	$	15,339	$	1,211
Operating income	$	29,815	$	27,116	$	2,699
Interest expense	$	9,158	$	8,670	$	488
Income before income taxes	$	20,657	$	18,446	$	2,211
Capital expenditures (including the effects of accruals)	$	56,481	$	53,199	$	3,282

			Reportable Segments
Nine Months Ended June 30, 2017	Total		Gas Utility		Electric Utility
Revenues	$	768,045	$	700,813	$	67,232
Cost of sales — gas, fuel and purchased power	$	325,991	$	288,610	$	37,381
Depreciation and amortization	$	53,002	$	49,378	$	3,624
Operating income	$	226,315	$	219,700	$	6,615
Interest expense	$	30,478	$	29,017	$	1,461
Income before income taxes	$	195,837	$	190,683	$	5,154
Capital expenditures (including the effects of accruals)	$	199,701	$	191,715	$	7,986
As of June 30, 2017
Total assets	$	2,904,532	$	2,743,035	$	161,497
Goodwill	$	182,145	$	182,145	$	—

			Reportable Segments
Nine Months Ended June 30, 2016	Total		Gas Utility		Electric Utility
Revenues	$	660,312	$	595,025	$	65,287
Cost of sales — gas, fuel and purchased power	$	257,288	$	221,646	$	35,642
Depreciation and amortization	$	50,281	$	46,665	$	3,616
Operating income	$	192,592	$	183,940	$	8,652
Interest expense	$	27,922	$	26,583	$	1,339
Income before income taxes	$	164,670	$	157,357	$	7,313
Capital expenditures (including the effects of accruals)	$	166,058	$	158,472	$	7,586
As of June 30, 2016
Total assets	$	2,697,301	$	2,531,573	$	165,728
Goodwill	$	182,145	$	182,145	$	—