RELATED PERSON TRANSACTIONS - Atlantic Automotive Corporation and Leased Property by Real Estate Venture (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Advertising time \| Atlantic Automotive
Related person transactions
Amount received	$ 0.2	$ 0.6
Leased assets or facilities \| Chief Executive Officer
Related person transactions
Amount received	$ 0.7	$ 0.6	$ 1.0

Reflects the sum of all other revenue and income realized from sales and other transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party during the period.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration