Borrowings and Other Financing Instruments (Tables)

9 Months Ended

Sep. 30, 2025

Borrowings and Other Financing Instruments [Abstract]

Credit Facilities

As of Sept. 30, 2025, SPS had the following committed revolving credit facility available (in millions of dollars):

Credit Facility (a)		Drawn (b)		Available
$	600	$	—	$	600

(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 Sept. 30, 2025		Year Ended Dec. 31, 2024
Borrowing limit	$	100	$	100
Amount outstanding at period end	—		7
Average amount outstanding	—		24
Maximum amount outstanding	—		100
Weighted average interest rate, computed on a daily basis	N/A		5.29		%
Weighted average interest rate at period end	N/A		4.58

Commercial Paper

Borrowings and Other Financing Instruments [Abstract]

Short-Term Borrowings

Commercial paper outstanding:

(Amounts in Millions, Except Interest Rates)	Three Months Ended Sept. 30, 2025		Year Ended Dec. 31, 2024
Borrowing limit	$	600	$	500
Amount outstanding at period end	—		145
Average amount outstanding	—		35
Maximum amount outstanding	—		160
Weighted average interest rate, computed on a daily basis	N/A		5.47		%
Weighted average interest rate at period end	N/A		4.66