ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)​ - Components of AOCI (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ 19,533	$ 21,813
Gain (loss) in other comprehensive income (loss) before reclassifications	(9)
(Gain) loss reclassified from accumulated other comprehensive income (loss)	3
Other comprehensive income (loss)	(6)	121
Balance at end of period	19,559	$ 21,631
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	29
Balance at end of period	23
Unrealized Gain (Loss) on Investment Securities, net
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(1)
Gain (loss) in other comprehensive income (loss) before reclassifications	(1)
(Gain) loss reclassified from accumulated other comprehensive income (loss)	0
Other comprehensive income (loss)	(1)
Balance at end of period	(2)
Foreign Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	126
Gain (loss) in other comprehensive income (loss) before reclassifications	(1)
(Gain) loss reclassified from accumulated other comprehensive income (loss)	0
Other comprehensive income (loss)	(1)
Balance at end of period	125
Pension and Other Post-retirement Benefit Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(27)
Gain (loss) in other comprehensive income (loss) before reclassifications	(3)
(Gain) loss reclassified from accumulated other comprehensive income (loss)	2
Other comprehensive income (loss)	(1)
Balance at end of period	(28)
Unrealized Gain (Loss) on Cash Flow Hedge Instruments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(69)
Gain (loss) in other comprehensive income (loss) before reclassifications	(4)
(Gain) loss reclassified from accumulated other comprehensive income (loss)	1
Other comprehensive income (loss)	(3)
Balance at end of period	$ (72)