TRANSFERS OF FINANCIAL ASSETS - Cash Proceeds (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Transfers and Servicing [Abstract]
Interests in conduits 1	$ 0	$ 211	$ 0	$ 656

Cash flows between transferee and transferor in payment of the transferor's beneficial interest related to a securitization, asset-backed financing arrangement, or similar transfer in which the transferor has continuing involvement with the transferred financial assets underlying the transaction.

No definition available.

Name:	us-gaap_CashFlowsBetweenTransferorAndTransfereeBeneficialInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration