There were no changes to the carrying amount of goodwill for the nine months ended September 30, 2021 (unaudited). The balances for each segment were as follows:

(millions)	Commercial		Aviation			Total
Net book value as of September 30, 2021 and December 31, 2020
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 expectations as of the October 1, 2019 annual impairment test. The Company did not know how long COVID-19 and its effects would continue to impact results of the Company. In addition, certain Aviation contracts were terminated during August 2020. The termination of these contracts and the ongoing impacts of COVID-19 on the Company’s expected future operating cash flows triggered the Company to complete a quantitative goodwill impairment analysis as of August 31, 2020 for the Aviation reporting unit. Accordingly, the Company determined the carrying value for the Aviation reporting unit was higher than its implied fair value. 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 $59.5 million of impairment charges during the three and nine months ended September 30, 2020, which were recognized in Impairment of goodwill and intangible assets in the Condensed Consolidated Statements of Income (Loss). The fair value of goodwill was classified as Level 3 in the fair value hierarchy.

No impairment charges were recorded during the three and nine months ended September 30, 2021.