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Intangible Franchise Rights and Goodwill - Narrative (Details) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2019 USD ($) | Sep. 30, 2019 USD ($) dealership | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Countries and States [Line Items] |  |  |  |
Goodwill impairment |  |  | $ 0 |
U.S. |  |  |  |
Countries and States [Line Items] |  |  |  |
Number of dealerships impaired | dealership |  | 1 |  |
Impairment charges | $ 10,400,000 | $ 3,000,000.0 |  |
Additions through acquisitions |  |  | $ 12,100,000 | $ 11,500,000
U.K. |  |  |  |
Countries and States [Line Items] |  |  |  |
Number of dealerships impaired | dealership |  | 7 |  |
Impairment charges |  | $ 5,600,000 |  |
Additions through acquisitions |  |  |  | $ 8,400,000

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- Definition Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13854-109267 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3602-108585 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 350 -SubTopic 20 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266 + Details
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