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Financial Instruments and Fair Value Measurements - Impact of Interest Rate Derivative Instruments (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Derivative [Line Items] |  |  |  |
Amount of unrealized income (loss), net of tax, recognized in other comprehensive (loss) income | $ (7.0) | $ (9.5) | $ (38.6) | $ (13.7)
Amount of income (loss) reclassified from other comprehensive (loss) income into statements of operations | $ (2.1) | $ 0.3 | (2.7) | 0.7
Floorplan interest expense, net |  |  |  |
Derivative [Line Items] |  |  |  |
Amount of income (loss) reclassified from other comprehensive (loss) income into statements of operations |  |  | (2.7) | 0.6
Other interest expense, net |  |  |  |
Derivative [Line Items] |  |  |  |
Amount of income (loss) reclassified from other comprehensive (loss) income into statements of operations |  |  | $ (0.8) | $ 0.2

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