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FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Narrative (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2021 USD ($) derivative	Sep. 30, 2021 USD ($) derivative	Jun. 30, 2021 USD ($) derivative	Dec. 31, 2020 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Amount expected to be reclassified from other comprehensive loss into earnings	$ (10,600,000)	$ (10,600,000)
Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Notional value			$ 250,000,000
Interest Rate Swaps
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Other deferred costs, net	$ 2,400,000	$ 2,400,000
Interest Rate Swaps \| Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Weighted average interest rate (as a percentage)			1.76%
Interest Rate Swaps \| Designated as Hedging Instrument \| Cash Flow Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Weighted average interest rate (as a percentage)	1.37%	1.37%
Interest Rate Swaps \| Floorplan interest expense \| Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Number of additional forward interest rate swaps \| derivative			5
Interest Rate Swaps \| Accumulated Other Comprehensive Income (Loss) \| Floorplan interest expense
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Tax portion of reclassification out of AOCI		$ 700,000
Interest Rate Swaps \| Accumulated Other Comprehensive Income (Loss) \| Floorplan interest expense \| Not Designated as Hedging Instrument
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Unrealized mark-to market gains	$ 1,000,000	2,000,000
Realized losses	$ 1,100,000	$ 2,100,000
Interest Rate Swaps \| Designated as Hedging Instrument \| Cash Flow Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Number of additional forward interest rate swaps \| derivative	33	33
Notional value	$ 686,100,000	$ 686,100,000
Interest Rate Swaps \| Designated as Hedging Instrument \| Cash Flow Hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Number of additional forward interest rate swaps \| derivative	8	8
Notional value	$ 425,000,000	$ 425,000,000
Weighted average interest rate (as a percentage)	1.20%	1.20%
Senior Notes \| 4.00% Senior Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Aggregate principle amount	$ 550,000,000	$ 550,000,000
Interest rate (as a percentage)	4.00%	4.00%
Demand notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Carrying value	$ 271,600,000	$ 271,600,000		$ 60,000,000