Segment Information (Tables)

3 Months Ended

Dec. 31, 2015

Segment Reporting [Abstract]

Schedule of Segment Information

Financial information by business segment follows:

Three Months Ended December 31, 2015:

			Reportable Segments
	Total		Gas Utility		Electric Utility
Revenues	$	197,982	$	176,942	$	21,040
Cost of sales	$	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	$	61,464	$	59,270	$	2,194
As of December 31, 2015
Total assets (at period end)	$	2,606,299	$	2,462,508	$	143,791
Goodwill (at period end)	$	182,145	$	182,145	$	—

Three Months Ended December 31, 2014:

			Reportable Segments
	Total		Gas Utility		Electric Utility		Other
Revenues	$	287,306	$	260,478	$	26,423	$	405
Cost of sales	$	143,052	$	127,208	$	15,844	$	—
Depreciation and amortization	$	15,425	$	14,280	$	1,145	$	—
Operating income	$	75,640	$	71,846	$	3,719	$	75
Interest expense	$	10,649	$	10,130	$	519	$	—
Income before income taxes	$	64,991	$	61,716	$	3,200	$	75
Capital expenditures	$	55,029	$	53,492	$	1,537	$	—
As of December 31, 2014
Total assets (at period end)	$	2,488,621	$	2,346,169	$	142,452	$	—
Goodwill (at period end)	$	182,145	$	182,145	$	—	$	—