BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounting Changes (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate2016-13Member
Retained earnings	$ 91,188	$ 87,732
Cumulative effect adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in allowance for credit losses		221
Retained earnings		$ (175)