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Selected Quarterly Financial Data (Unaudited) - Narrative (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2018 | Sep. 30, 2018 | Jun. 30, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract] |  |  |  |  |  |  |  |
Asset impairment charges | $ 16,500 | $ 23,200 | $ 4,300 | $ 10,000 | $ 9,500 | $ 43,883 | $ 19,506 | $ 32,838
Net pre-tax gain (loss) on dealership dispositions |  |  | $ 20,200 |  |  |  |  |
Chargeback reserves for finance and insurance revenues related to catastrophic events |  |  |  |  | $ 14,700 |  |  |
Provisional tax benefit related to re-measurement of deferred tax assets and liabilities as a result of the U.S. tax reform bill | $ 73,000 |  |  |  |  |  |  |

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- Definition Net Gain (Loss) on Real Estate and Dealership Transactions + References No definition available. + Details
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- Definition Tax Cuts And Jobs Act, Measurement Period Adjustment, Income Tax Expense (Benefit) + References No definition available. + Details
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- Definition Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill. + References Reference 1: 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=109223946&loc=d3e3602-108585 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109226348&loc=d3e2420-110228 + Details
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