Benefit Plans and Other Postretirement Benefits, Postretirement Benefit Plan Benefit Obligations, Cash Flows and Benefit Costs (Details) - USD ($)		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Significant Assumptions Used to Measure Costs [Abstract]
Liability, Defined Benefit Plan, Noncurrent		$ 23,000,000		$ 161,000,000
Defined Contribution Plan, Administrative Expense		12,000,000		12,000,000		$ 11,000,000
Other Postretirement Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value		68,000,000	[1]	61,000,000	[2]
Plan amendments		0		0
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		415,000,000
Service cost		1,000,000		1,000,000		1,000,000
Interest cost		11,000,000		13,000,000		15,000,000
Medicare subsidy reimbursements		2,000,000		1,000,000
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant		7,000,000		6,000,000
Actuarial (gain) loss		(31,000,000)		52,000,000
Benefit payments		(36,000,000)		(38,000,000)
Obligation at Dec. 31		369,000,000		415,000,000
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	[2]	404,000,000
Actual return (loss) on plan assets		15,000,000		32,000,000
Plan participants' contributions		7,000,000		6,000,000
Employer contributions		3,000,000		3,000,000
Benefit payments		(36,000,000)		(38,000,000)
Fair value of plan assets at Dec. 31		393,000,000	[1]	404,000,000	[2]
Funded Status of Plans at Dec. 31 [Abstract]
Funded status		24,000,000		(11,000,000)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss		48,000,000		81,000,000
Prior service (credit) cost		2,000,000		6,000,000
Total		46,000,000		75,000,000
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Noncurrent regulatory assets		$ 46,000,000		$ 75,000,000
Significant Assumptions Used to Measure Benefit Obligations [Abstract]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Pre-65		5.30%		5.50%
Ultimate health care trend assumption rate (as a percent)		4.50%		4.50%
Period until ultimate trend rate is reached (in years)		4		5
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		$ 1,000,000		$ 1,000,000		1,000,000
Interest cost		11,000,000		13,000,000		15,000,000
Expected return on plan assets		(16,000,000)		(17,000,000)		(19,000,000)
Amortization of prior service (credit) cost		(4,000,000)		(4,000,000)		(5,000,000)
Amortization of net loss		3,000,000		1,000,000		3,000,000
Net periodic pension cost		$ (5,000,000)		$ (7,000,000)		$ (5,000,000)
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)		2.65%		3.47%		4.32%
Expected average long-term rate of return on assets (as a percent)		4.10%		4.50%		4.50%
Liability, Defined Benefit Plan, Noncurrent		$ 0		$ (11,000,000)
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position		$ 24,000,000		$ (11,000,000)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		3.09%		2.65%
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Current Regulatory Assets		$ 0		$ 0
Deferred Income Taxes		0		0
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Net-Of-Tax Accumulated Other Comprehensive Income		0		0
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	[3]	0		0		$ 0
Defined Benefit Plan, Costs Not Recognized Due To Regulation		2,000,000		3,000,000		1,000,000
Net benefit cost recognized for financial reporting		$ (3,000,000)		$ (4,000,000)		(4,000,000)
Target pension asset allocations (as a percent)		100.00%		100.00%
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months		$ 30,000,000
Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, Next Twelve Months		2,000,000
Defined Benefit Plan Net Projected Benefit Payments In Year One		28,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Two		29,000,000
Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, Year Two		2,000,000
Defined Benefit Plan Net Projected Benefit Payments In Year Two		27,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Three		29,000,000
Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, Year Three		2,000,000
Defined Benefit Plan Net Projected Benefit Payments In Year Three		27,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Four		28,000,000
Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, Year Four		2,000,000
Defined Benefit Plan Net Projected Benefit Payments In Year Four		26,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Five		27,000,000
Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, Year Five		2,000,000
Defined Benefit Plan Net Projected Benefit Payments In Year Five		25,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter		123,000,000
Defined Benefit Plan, Expected Future Prescription Drug Subsidy Receipt, after Year Five		13,000,000
Defined Benefit Plan Net Projected Benefit Payments In Five Fiscal Years Thereafter		$ 110,000,000
Other Postretirement Benefits Plan [Member] | Domestic and international equity securities
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		15.00%		15.00%
Other Postretirement Benefits Plan [Member] | Long-Duration Fixed Income and Interest Rate Swap Securities [Member]
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		0.00%		0.00%
Other Postretirement Benefits Plan [Member] | Short-to-intermediate fixed income securities
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		71.00%		72.00%
Other Postretirement Benefits Plan [Member] | Alternative investments
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		8.00%		9.00%
Other Postretirement Benefits Plan [Member] | Cash
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value		$ 0	[1]	$ 0	[2]
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	[2]	24,000,000
Fair value of plan assets at Dec. 31		$ 25,000,000	[1]	$ 24,000,000	[2]
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		6.00%		4.00%
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value		$ 421,000,000	[2]	$ 388,000,000	[1]
Plan amendments		0		0
Change in Projected Benefit Obligation [Roll Forward]
Obligation at Jan. 1		1,428,000,000
Service cost		32,000,000		30,000,000		26,000,000
Interest cost		39,000,000		46,000,000		52,000,000
Medicare subsidy reimbursements		0		0
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant		0		0
Actuarial (gain) loss		(57,000,000)		102,000,000
Benefit payments		(79,000,000)		(80,000,000)
Obligation at Dec. 31		1,363,000,000		1,428,000,000
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	[1]	1,283,000,000
Actual return (loss) on plan assets		102,000,000		189,000,000
Plan participants' contributions		0		0
Employer contributions		45,000,000		50,000,000
Benefit payments		(79,000,000)		(80,000,000)
Fair value of plan assets at Dec. 31		1,351,000,000	[2]	1,283,000,000	[1]
Funded Status of Plans at Dec. 31 [Abstract]
Funded status		(12,000,000)		(145,000,000)
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost [Abstract]
Net loss		313,000,000		432,000,000
Prior service (credit) cost		1,000,000		1,000,000
Total		312,000,000		431,000,000
Amounts Not Yet Recognized as Components of Net Periodic Benefit Cost Have Been Recorded as Follows Based Upon Expected Recovery in Rates [Abstract]
Noncurrent regulatory assets		288,000,000		404,000,000
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service cost		32,000,000		30,000,000		26,000,000
Interest cost		39,000,000		46,000,000		52,000,000
Expected return on plan assets		(73,000,000)		(70,000,000)		(69,000,000)
Amortization of prior service (credit) cost		0		(3,000,000)		(3,000,000)
Amortization of net loss		32,000,000		30,000,000		25,000,000
Net periodic pension cost		$ 30,000,000		$ 33,000,000		$ 34,000,000
Significant Assumptions Used to Measure Costs [Abstract]
Discount rate (as a percent)		2.71%		3.49%		4.31%
Expected average long-term rate of return on assets (as a percent)		6.38%		6.84%		6.84%
Liability, Defined Benefit Plan, Noncurrent		$ 18,000,000		$ 145,000,000
Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position		$ (12,000,000)		$ (145,000,000)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		3.08%		2.71%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase		3.75%		3.75%
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Current Regulatory Assets		$ 24,000,000		$ 25,000,000
Deferred Income Taxes		0		1,000,000
Amounts Not Yet Recognized As Components Of Net Periodic Benefit Cost Recorded As Net-Of-Tax Accumulated Other Comprehensive Income		0		1,000,000
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement	[3]	0		0		$ 3,000,000
Defined Benefit Plan, Costs Not Recognized Due To Regulation		0		4,000,000		4,000,000
Net benefit cost recognized for financial reporting		$ 30,000,000		$ 37,000,000		$ 38,000,000
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase		3.75%		3.75%		3.75%
Target pension asset allocations (as a percent)		100.00%		100.00%
Defined Benefit Plan, Expected Future Benefit Payment, Next Twelve Months		$ 83,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Two		82,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Three		82,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Four		82,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Year Five		81,000,000
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter		388,000,000
Pension Plan [Member] | Domestic and international equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value		0	[2]	$ 0	[1]
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	[1]	27,000,000
Fair value of plan assets at Dec. 31		$ 24,000,000	[2]	$ 27,000,000	[1]
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		33.00%		35.00%
Pension Plan [Member] | Long-Duration Fixed Income and Interest Rate Swap Securities [Member]
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		37.00%		35.00%
Pension Plan [Member] | Short-to-intermediate fixed income securities
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		11.00%		13.00%
Pension Plan [Member] | Alternative investments
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		17.00%		15.00%
Pension Plan [Member] | Cash
Defined Benefit Plan Disclosure [Line Items]
Plan assets at net asset value		$ 0	[2]	$ 0	[1]
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	[1]	75,000,000
Fair value of plan assets at Dec. 31		$ 49,000,000	[2]	$ 75,000,000	[1]
Significant Assumptions Used to Measure Costs [Abstract]
Target pension asset allocations (as a percent)		2.00%		2.00%

[1] See Note 8 for further information on fair value measurement inputs and methods.

[2] See Note 8 for further information on fair value measurement inputs and methods.

[3] A settlement charge is required when the amount of all lump-sum distributions during the year is greater than the sum of the service and interest cost components of the annual net periodic pension cost. In 2019, as a result of lump-sum distributions during the plan year, PSCo recorded a total pension settlement charge of $3 million. An immaterial amount was recorded in the income statement in 2019. There were no settlement charges recorded to the qualified pension plans in 2021 or 2020