RELATED PERSON TRANSACTIONS - Atlantic Automotive Corporation (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018 USD ($) real_estate_venture	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) real_estate_venture	Jun. 30, 2017 USD ($)
Lease Services | Atlantic Automotive Corporation
Related Party Transaction [Line Items]
Amount received		$ 0.1		$ 0.4
Atlantic Automotive Corporation | Lease Services | Affiliated Entity | Real estate ventures in Towson, MD
Related Party Transaction [Line Items]
Number of consolidated real estate ventures | real_estate_venture	1		1
Maximum | Atlantic Automotive Corporation | Advertising time | Affiliated Entity
Related Party Transaction [Line Items]
Amount received	$ 0.1	$ 0.2	$ 0.1	$ 0.3