Segment Information (Tables)

6 Months Ended

Jun. 30, 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 June 30, 2018
Operating revenues from external customers	$	2,348	$	292	$	18		$	—	$	2,658
Intersegment revenues	—		—		—			—		—
Total revenues	$	2,348	$	292	$	18		$	—	$	2,658
Net income (loss)	$	264	$	27	$	(26	)	$	—	$	265

(Millions of Dollars)	Regulated Electric		Regulated Natural Gas		All Other			Reconciling Eliminations			Consolidated Total
Three Months Ended June 30, 2017
Operating revenues from external customers	$	2,338	$	290	$	17		$	—		$	2,645
Intersegment revenues	1		—		—			(1		)	—
Total revenues	$	2,339	$	290	$	17		$	(1	)	$	2,645
Net income (loss)	$	227	$	13	$	(13	)	$	—		$	227

(Millions of Dollars)	Regulated Electric		Regulated Natural Gas		All Other			Reconciling Eliminations			Consolidated Total
Six Months Ended June 30, 2018
Operating revenues from external customers	$	4,617	$	954	$	38		$	—		$	5,609
Intersegment revenues	1		1		—			(2		)	—
Total revenues	$	4,618	$	955	$	38		$	(2	)	$	5,609
Net income (loss)	$	483	$	121	$	(48	)	$	—		$	556

(Millions of Dollars)	Regulated Electric		Regulated Natural Gas		All Other			Reconciling Eliminations			Consolidated Total
Six Months Ended June 30, 2017
Operating revenues from external customers	$	4,637	$	915	$	39		$	—		$	5,591
Intersegment revenues	1		1		—			(2		)	—
Total revenues	$	4,638	$	916	$	39		$	(2	)	$	5,591
Net income (loss)	$	422	$	76	$	(31	)	$	—		$	467