Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2021

Commitments And Contingencies Disclosure [Abstract]

Summary of Activities Relating to Company's CARO Liabilities

The following table summarizes activity relating to CARO liabilities (in millions of dollars):

	Year Ended December 31,
	2021			2020			2019
Beginning balance	$	6.7		$	6.5		$	6.3
Liabilities settled during the period		(0.1	)		(0.1	)		(0.2	)
Accretion expense		0.6			0.5			0.5
Adjustment to accretion expense due to revisions to    estimated cash flow and timing of expenditure1		—			(0.2	)		(0.1	)
Ending balance	$	7.2		$	6.7		$	6.5

^1. The adjustments to accretion expense had a $0.01 impact on the basic and diluted net income per share for both 2020 and 2019.

Schedule of Changes in Environmental Contingencies

The following table presents the changes in our environmental accrual, which was primarily included in Long-term liabilities (in millions of dollars):

	Year Ended December 31,
	2021			2020			2019
Beginning balance	$	18.7		$	17.0		$	16.9
Additional accruals		0.1			5.2			1.8
Less: expenditures		(2.0	)		(3.5	)		(1.7	)
Ending balance	$	16.8		$	18.7		$	17.0