Borrowings and Other Financing Instruments (Tables)

3 Months Ended

Mar. 31, 2026

Borrowings and Other Financing Instruments [Abstract]

Credit Facilities

As of March 31, 2026, SPS had the following committed revolving credit facility available (in millions of dollars):

Credit Facility (a)		Drawn (b)		Available
$	600	$	55	$	545

(a)Expires in December 2029.

(b)Includes outstanding letters of credit.

Money Pool

Borrowings and Other Financing Instruments [Abstract]

Short-Term Borrowings

Money pool borrowings:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2026			Year Ended Dec. 31, 2025
Borrowing limit	$	100		$	100
Amount outstanding at period end	—			62
Average amount outstanding	48			31
Maximum amount outstanding	100			100
Weighted average interest rate, computed on a daily basis	3.64		%	4.19		%
Weighted average interest rate at period end	N/A			3.88

Commercial Paper

Borrowings and Other Financing Instruments [Abstract]

Short-Term Borrowings

Commercial paper outstanding:

(Amounts in Millions, Except Interest Rates)	Three Months Ended March 31, 2026			Year Ended Dec. 31, 2025
Borrowing limit	$	600		$	600
Amount outstanding at period end	55			220
Average amount outstanding	206			97
Maximum amount outstanding	350			314
Weighted average interest rate, computed on a daily basis	3.94		%	4.51		%
Weighted average interest rate at period end	4.20			3.93