COMMITMENTS AND CONTINGENCIES (Other Contractual Obligations) (Details) £ in Millions, $ in Millions	Dec. 31, 2019 USD ($)	Dec. 31, 2019 GBP (£)	Dec. 31, 2018 ft²
Headquarters | Manchester, England [Member] | Rentalcars.com [Member]
Other Commitments [Line Items]
Area of property subject to lease (in square feet) | ft²			222,000
Term of lease not yet commenced	13 years	13 years
Operating lease obligations | Headquarters | Manchester, England [Member] | Rentalcars.com [Member]
Other Commitments [Line Items]
Lease obligation for lease not yet commenced, excluding lease incentives	$ 86	£ 65
Standby Letters of Credit [Member]
Other Commitments [Line Items]
Letters of credit outstanding | $	$ 155