OPERATING SEGMENTS - Assets by Geographic Area (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 253,452	$ 265,177
Continuing Operations
Segment Reporting Information [Line Items]
Assets	249,920	261,068	$ 246,686
Continuing Operations | U.S.
Segment Reporting Information [Line Items]
Assets	148,963	143,534
Continuing Operations | Europe
Segment Reporting Information [Line Items]
Assets	58,301	70,565
Continuing Operations | Asia
Segment Reporting Information [Line Items]
Assets	20,630	22,089
Continuing Operations | Americas
Segment Reporting Information [Line Items]
Assets	10,795	13,435
Continuing Operations | Other Global
Segment Reporting Information [Line Items]
Assets	11,230	11,445
Continuing Operations | Total Non-U.S.
Segment Reporting Information [Line Items]
Assets	$ 100,956	$ 117,534