Revenues (Tables)

3 Months Ended

Mar. 31, 2018

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

In the following tables, revenue is classified by the type of goods/services rendered and market/customer type. The tables also reconcile revenue to the reportable segments.

	Three Months Ended March 31, 2018
(Millions of Dollars)	Regulated Electric		Regulated Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	687	$	390	$	9	$	1,086
Commercial and industrial (C&I)	1,112		207		7		1,326
Other	33		—		1		34
Total retail	1,832		597		17		2,446
Wholesale	188		—		—		188
Transmission	123		—		—		123
Other	39		28		—		67
Total revenue from contracts with customers	2,182		625		17		2,824
Alternative revenue and other	88		37		2		127
Total revenues	$	2,270	$	662	$	19	$	2,951

	Three Months Ended March 31, 2017
(Millions of Dollars)	Regulated Electric		Regulated Natural Gas		All Other		Total
Major revenue types
Revenue from contracts with customers:
Residential	$	685	$	374	$	8	$	1,067
C&I	1,148		195		9		1,352
Other	32		—		1		33
Total retail	1,865		569		18		2,452
Wholesale	181		—		—		181
Transmission	121		—		—		121
Other	25		25		—		50
Total revenue from contracts with customers	2,192		594		18		2,804
Alternative revenue and other	107		32		3		142
Total revenues	$	2,299	$	626	$	21	$	2,946