GOODWILL AND OTHER INTANGIBLE ASSETS - Summary of Amortization Expense (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 100	$ 117	$ 320	$ 353
Other intangible assets, excluding software
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	100	117	320	353
Software
Finite-Lived Intangible Assets [Line Items]
Amortization of intangibles	$ 23	$ 23	$ 70	$ 68

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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