Selected Balance Sheet Data (Tables)

9 Months Ended

Sep. 30, 2021

Balance Sheet Related Disclosures [Abstract]

Accounts Receivable, Net

(Millions of Dollars)	Sept. 30, 2021		Dec. 31, 2020
Accounts receivable, net
Accounts receivable	$	401	$	371
Less allowance for bad debts	(38)		(29)
Accounts receivable, net	$	363	$	342

Inventories

(Millions of Dollars)	Sept. 30, 2021		Dec. 31, 2020
Inventories
Materials and supplies	$	66	$	63
Fuel	73		73
Natural gas	92		53
Total inventories	$	231	$	189

Property, Plant and Equipment, Net

(Millions of Dollars)	Sept. 30, 2021		Dec. 31, 2020
Property, plant and equipment, net
Electric plant	$	16,265	$	15,736
Natural gas plant	5,267		5,037
Common and other property	1,176		1,191
Plant to be retired (a)	186		225
Construction work in progress	799		510
Total property, plant and equipment	23,693		22,699
Less accumulated depreciation	(5,573)		(5,229)
Property, plant and equipment, net	$	18,120	$	17,470

(a)Includes regulator-approved retirements of Comanche Units 1 and 2 and jointly owned Craig Unit 1. Also includes PSCo’s planned retirement of jointly owned Craig Unit 2.