DEBT - Debt Securities, Trading, and Equity Securities, FV-NI (Details) - 2021 Convertible Notes - Convertible Debt - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Jul. 31, 2021
Debt Instrument [Line Items]
Fair value (carrying amount)	$ 2,958,000,000	$ 2,958,000,000
Unpaid principal balance	2,500,000,000	2,500,000,000	$ 2,500,000,000
Loss on convertible notes, net	$ 458,000,000	$ 458,000,000