Segment Information (Tables)

3 Months Ended

Dec. 31, 2016

Segment Reporting [Abstract]

Schedule of Segment Information

Financial information by business segment follows:

Three Months Ended December 31, 2016:

			Reportable Segments
	Total		Gas Utility		Electric Utility
Revenues	$	261,413	$	237,100	$	24,313
Cost of sales — gas, fuel and purchased power	$	109,471	$	95,567	$	13,904
Depreciation and amortization	$	17,391	$	16,155	$	1,236
Operating income	$	82,236	$	78,967	$	3,269
Interest expense	$	10,028	$	9,583	$	445
Income before income taxes	$	72,208	$	69,384	$	2,824
Capital expenditures (including the effects of accruals)	$	64,096	$	61,742	$	2,354
As of December 31, 2016
Total assets (at period end)	$	2,898,523	$	2,736,908	$	161,615
Goodwill (at period end)	$	182,145	$	182,145	$	—

Three Months Ended December 31, 2015:

			Reportable Segments
	Total		Gas Utility		Electric Utility
Revenues	$	197,982	$	176,942	$	21,040
Cost of sales — gas, fuel and purchased power	$	75,439	$	64,229	$	11,210
Depreciation and amortization	$	16,701	$	15,504	$	1,197
Operating income	$	48,296	$	45,820	$	2,476
Interest expense	$	9,494	$	9,066	$	428
Income before income taxes	$	38,802	$	36,754	$	2,048
Capital expenditures (including the effects of accruals)	$	61,464	$	59,270	$	2,194
As of December 31, 2015
Total assets (at period end)	$	2,604,168	$	2,460,482	$	143,686
Goodwill (at period end)	$	182,145	$	182,145	$	—