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Financial Instruments and Fair Value Measurements - Impact of Interest Rate Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Derivative [Line Items]
Amount of unrealized income (loss), net of tax, recognized in other comprehensive (loss) income	$ (9,454)	$ 3,414	$ (13,691)	$ 11,305
Amount of income (loss) reclassified from other comprehensive (loss) income into statements of operations	$ 307	$ (1,062)	654	(2,576)
Floorplan interest expense, net
Derivative [Line Items]
Amount of income (loss) reclassified from other comprehensive (loss) income into statements of operations			618
Amount of income (loss) reclassified from other comprehensive (loss) income into statements of operations				(2,999)
Other interest expense, net
Derivative [Line Items]
Amount of income (loss) reclassified from other comprehensive (loss) income into statements of operations			$ 239
Amount of income (loss) reclassified from other comprehensive (loss) income into statements of operations				$ (390)

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Amount, after tax and before reclassification, of gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Amount, after tax, of reclassification of gain (loss) from accumulated other comprehensive income (AOCI) for derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness.

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Amount after tax of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

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