Summary of Significant Accounting Policies Inventory (Tables)

12 Months Ended

Dec. 31, 2019

Balance Sheet Related Disclosure - Inventory [Abstract]

Public Utilities, Inventory

nventory is recorded at average cost and consisted of the following:

(Millions of Dollars)	Dec. 31, 2019		Dec. 31, 2018
Inventories
Materials and supplies	$	6.8	$	6.7
Fuel	4.0		3.8
Natural gas	5.2		6.6
Total inventories	$	16.0	$	17.1