Summary of Significant Accounting Policies Inventory (Tables)

12 Months Ended

Dec. 31, 2023

Balance Sheet Related Disclosure - Inventory [Abstract]

Schedule of Utility Inventory [Table Text Block]

Inventory — Inventory is recorded at the lower of average cost or net realizable value and consisted of the following:

(Millions of Dollars)	Dec. 31, 2023		Dec. 31, 2022
Inventories
Materials and supplies	$	56	$	42
Fuel	13		19
Total inventories	$	69	$	61