ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 23,420	$ 22,673
Other comprehensive income (loss) before reclassifications	(1,568)	(328)
Amounts reclassified to the Consolidated Statements of Operations	(25)	(23)
Total other comprehensive income (loss), net of income taxes	(1,593)	(351)
Ending balance	22,074	22,653
Total AOCI
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(665)	(60)
Total other comprehensive income (loss), net of income taxes	(1,593)	(351)
Ending balance	(2,258)	(411)
Net Unrealized Gains (Losses) on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(161)	(11)
Other comprehensive income (loss) before reclassifications	(491)	(21)
Amounts reclassified to the Consolidated Statements of Operations	(24)	(25)
Total other comprehensive income (loss), net of income taxes	(515)	(46)
Ending balance	(676)	(57)
Net Unrealized Gains (Losses) on Debt Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(156)	380
Other comprehensive income (loss) before reclassifications	(1,077)	(307)
Amounts reclassified to the Consolidated Statements of Operations	(3)	(2)
Total other comprehensive income (loss), net of income taxes	(1,080)	(309)
Ending balance	(1,236)	71
Employee Benefit Plans
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(348)	(429)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified to the Consolidated Statements of Operations	2	4
Total other comprehensive income (loss), net of income taxes	2	4
Ending balance	$ (346)	$ (425)