Segment Information (Tables)

3 Months Ended

Mar. 31, 2018

Segment Reporting [Abstract]

Results from Operations by Reportable Segment

(Millions of Dollars)	Regulated Electric		Regulated Natural Gas		All Other			Reconciling Eliminations			Consolidated Total
Three Months Ended March 31, 2018
Operating revenues from external customers	$	2,270	$	662	$	19		$	—		$	2,951
Intersegment revenues	—		—		—			—			—
Total revenues	$	2,270	$	662	$	19		$	—		$	2,951
Net income (loss)	$	219	$	95	$	(22	)	$	(1	)	$	291

(Millions of Dollars)	Regulated Electric		Regulated Natural Gas		All Other			Reconciling Eliminations		Consolidated Total
Three Months Ended March 31, 2017
Operating revenues from external customers	$	2,299	$	626	$	21		$	—	$	2,946
Intersegment revenues	—		—		—			—		—
Total revenues	$	2,299	$	626	$	21		$	—	$	2,946
Net income (loss)	$	194	$	63	$	(18	)	$	—	$	239