Segments and Related Information (Tables)

12 Months Ended

Dec. 31, 2019

Segment Reporting [Abstract]

Results from Operations by Reportable Segment

(Millions of Dollars)	2019			2018			2017
Regulated Electric
Operating revenues (a)	$	844.1		$	878.6		$	881.9
Intersegment revenues	0.3			0.4			0.5
Total operating revenue	$	844.4		$	879.0		$	882.4
Depreciation and amortization	108.4			97.8			88.9
Interest charges and financing costs	34.2			31.8			29.4
Income tax expense	12.5			28.4			38.9
Net income	68.5			85.5			70.9
Regulated Natural Gas
Operating revenues (a)	$	136.4		$	141.6		$	122.4
Intersegment revenues	0.4			0.4			0.3
Total operating revenue	$	136.8		$	142.0		$	122.7
Depreciation and amortization	29.0			28.1			22.1
Interest charges and financing costs	3.9			3.3			2.8
Income tax expense	2.2			4.5			4.0
Net income	9.9			12.5			7.8
Other
Operating revenues (a)	$	0.4		$	1.3		$	1.2
Depreciation and amortization	0.1			0.2			0.2
Interest charges and financing costs	—			0.1			—
Income tax expense (benefit)	1.0			(0.6		)	1.3
Net income	0.5			—			0.7
Consolidated Total
Total operating revenue (a)	$	981.6		$	1,022.3		$	1,006.3
Reconciling eliminations	(0.7		)	(0.8		)	(0.8		)
Consolidated total revenue	$	980.9		$	1,021.5		$	1,005.5
Depreciation and amortization	137.5			126.1			111.2
Interest charges and financing costs	38.1			35.2			32.2
Income tax expense	15.7			32.3			44.2
Net income	78.9			98.0			79.4

^(a) 

Operating revenues include $176.6 million, $157.9 million and $177.2 million of intercompany revenue for the years ended Dec. 31, 2019, 2018 and 2017, respectively. See Note 13 for further information.