Borrowings and Other Financing Instruments (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Money Pool [Table Text Block]

Money pool borrowings for PSCo were as follows:

(Millions of Dollars, Except Interest Rates)	Three Months Ended Dec. 31, 2020			Year Ended Dec. 31
				2020			2019			2018
Borrowing limit	$	250		$	250		$	250		$	250
Amount outstanding at period end	57			57			39			—
Average amount outstanding	104			59			7			25
Maximum amount outstanding	218			250			50			156
Weighted average interest rate, computed on a daily basis	0.08		%	0.60		%	2.29		%	1.93		%
Weighted average interest rate at end of period	0.07			0.07			1.63			N/A

Schedule of Short-term Debt [Table Text Block]

Commercial paper borrowings for PSCo were as follows:

(Millions of Dollars, Except Interest Rates)	Three Months Ended Dec. 31, 2020			Year Ended Dec. 31
				2020			2019			2018
Borrowing limit	$	700		$	700		$	700		$	700
Amount outstanding at period end	136			136			—			307
Average amount outstanding	8			30			154			55
Maximum amount outstanding	136			230			432			309
Weighted average interest rate, computed on a daily basis	0.19		%	1.59		%	2.67		%	2.28		%
Weighted average interest rate at end of period	0.20			0.20			N/A			2.95

Schedule Of Debt To Total Capitalization Ratio [Table Text Block]

Debt-to-Total Capitalization Ratio (a)				Amount Facility May Be Increased (millions)		Additional Periods for Which a One-Year Extension May Be Requested (b)
2020		2019
44	%	44	%	$	100	2

Schedule of Line of Credit Facilities [Table Text Block]

(millions):

Credit Facility (a)		Drawn (b)		Available
$	700	$	144	$	556

(a)This credit facility matures in June 2024.

(b)Includes letters of credit and outstanding commercial paper.

^[1],[2]

Schedule of Capitalization [Table Text Block]

Long-term debt obligations for PSCo as of Dec. 31 (millions of dollars):

Financing Instrument	Interest Rate	Maturity Date	2020		2019
First mortgage bonds	3.20	Nov. 15, 2020	—		400
First mortgage bonds	2.25	Sept. 15, 2022	300		300
First mortgage bonds	2.50	March 15, 2023	250		250
First mortgage bonds	2.90	May 15, 2025	250		250
First mortgage bonds	3.70	June 15, 2028	350		350
First mortgage bonds (a)	1.90	Jan. 15, 2031	375		—
First mortgage bonds	6.25	Sept. 1, 2037	350		350
First mortgage bonds	6.50	Aug. 1, 2038	300		300
First mortgage bonds	4.75	Aug. 15, 2041	250		250
First mortgage bonds	3.60	Sept. 15, 2042	500		500
First mortgage bonds	3.95	March 15, 2043	250		250
First mortgage bonds	4.30	March 15, 2044	300		300
First mortgage bonds	3.55	June 15, 2046	250		250
First mortgage bonds	3.80	June 15, 2047	400		400
First mortgage bonds	4.10	June 15, 2048	350		350
First mortgage bonds (b)	4.05	Sept. 15, 2049	400		400
First mortgage bonds (b)	3.20	March 1, 2050	550		550
First mortgage bonds (a)	2.70	Jan. 15, 2051	375		—
Unamortized discount			(30)		(24)
Unamortized debt issuance cost			(46)		(41)
Current maturities			—		(400)
Total long-term debt			$	5,724	$	4,985

^[3],[4]

Schedule of Maturities of Long-term Debt [Table Text Block]

Maturities of long-term debt:

(Millions of Dollars)
2021	$	—
2022	300
2023	250
2024	—
2025	250

Preferred Stock

Capital Stock — PSCo has authorized the issuance of preferred stock.

Preferred Stock Authorized (Shares)	Par Value of Preferred Stock		Preferred Stock Outstanding (Shares) 2020 and 2019
10,000,000	$	0.01	—

[1] Includes letters of credit and outstanding commercial paper.

[2] This credit facility matures in June 2024.

[3] 2019 financing.

[4] 2020 financing