FINANCIAL INSTRUMENTS - Assets and Liabilities Not Carried at Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Carrying amount (net)
Assets
Notes receivable	$ 3,842	$ 4,113
Liabilities
Borrowings	75,067	90,882
Investment contracts	2,049	2,191
Estimated fair value
Assets
Notes receivable	3,970	4,208
Liabilities
Borrowings	86,171	97,754
Investment contracts	2,547	2,588
Accrued interest	$ 898	$ 1,106