LEASES - Balance Sheet Classification (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease assets [Extensible List]	us-gaap:OtherAssets	us-gaap:OtherAssets
Operating lease assets	$ 272	$ 324
Operating lease liabilities [Extensible List]	us-gaap:OtherLiabilities	us-gaap:OtherLiabilities
Operating lease liabilities	$ 350	$ 415