LEASES - Lease Cost (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Leases [Abstract]
Amortization of assets	$ 73
Interest on lease liabilities	19
Total finance lease costs	92
Variable lease costs	206
Short-term lease costs	1,122
Operating lease costs	643
Total lease costs	$ 2,063