Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2025

Asset Retirement Obligation Disclosure [Abstract]

Schedule of Reconciliation of ARO

A reconciliation of the beginning and ending aggregate carrying amount of the ARO is shown in the following table:

	December 31,
(Millions of dollars)	2025		2024
Balance at beginning of period	$	49.1	$	46.1
Accretion expense	3.4		3.2
Settlement of liabilities	(1.0)		(3.1)
Liabilities incurred	1.0		2.9
Balance at end of period	$	52.5	$	49.1