The changes in the carrying amounts of goodwill for the years ended December 31, 2021 and 2020 were as follows:

(millions)	Commercial		Aviation			Total
Net book values as of January 1, 2020
Goodwill	$	377.0	$	209.0		$	586.0
Accumulated impairment losses		—		—			—
Total	$	377.0	$	209.0		$	586.0
Impairment		—		(59.5	)		(59.5	)
Foreign currency translation	$	0.1	$	—		$	0.1
Net book value as of December 31, 2020
Goodwill	$	377.1	$	209.0		$	586.1
Accumulated impairment losses		—		(59.5	)		(59.5	)
Total	$	377.1	$	149.5		$	526.6
Net book value as of December 31, 2021
Goodwill	$	377.1	$	209.0		$	586.1
Accumulated impairment losses		—		(59.5	)		(59.5	)
Total	$	377.1	$	149.5		$	526.6

As discussed in Note 1. Significant Accounting Policies and Practices, due to the impacts of COVID-19, revenues for certain markets in which the Company operates dropped significantly during 2020 as compared to the expectations as of the October 1, 2019 annual impairment test. The implied fair value was determined based on cash flow projections that assume certain future revenue and cost levels, comparable marketplace data, assumed discount rates based upon current market conditions and other valuation factors. As a result, the Company recorded a $59.5 million impairment charge during the year ended December 31, 2020, which was recognized in Impairment of goodwill and intangible assets in the Consolidated Statements of Income (Loss). The fair value of goodwill was classified as Level 3 in the fair value hierarchy. See Note 11 Fair Value Measurement for further discussion.

No impairment charges were recorded during the years ended December 31, 2021 and 2019.