Goodwill

12 Months Ended

Dec. 31, 2023

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill

9. Goodwill

The changes in the carrying amounts of goodwill during the years ended December 31, 2023 and 2022 were as follows:

(millions)	Commercial			Aviation			Total
Net book values as of January 1, 2022
Goodwill	$	377.1		$	209.0		$	586.1
Accumulated impairment losses		—			(59.5	)		(59.5	)
Total	$	377.1		$	149.5		$	526.6
Acquisitions		10.1			6.2			16.3
Foreign currency translation		(0.2	)		0.5			0.3
Net book value as of December 31, 2022
Goodwill	$	387.0		$	215.7		$	602.7
Accumulated impairment losses		—			(59.5	)		(59.5	)
Total	$	387.0		$	156.2		$	543.2
Acquisitions		1.0			—			1.0
Foreign currency translation		0.1			0.3			0.4
Net book value as of December 31, 2023
Goodwill	$	388.1		$	216.0		$	604.1
Accumulated impairment losses		—			(59.5	)		(59.5	)
Total	$	388.1		$	156.5		$	544.6