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ACCUMULATED OTHER COMPREHENSIVE (LOSS) INCOME - Schedule of Changes in Components of AOCI (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2024 | Jun. 30, 2023 | Jun. 30, 2024 | Jun. 30, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |
Beginning balance, shareholders' equity | $ 21,848 | $ 19,216 | $ 21,255 | $ 9,662
AOCI activity before reclassifications |  |  |  | (50)
Amounts reclassified from AOCI to earnings |  |  |  | 13
Other comprehensive loss, net of tax | (28) | (103) | (119) | (37)
Ending balance, shareholders' equity | 22,487 | 19,771 | 22,487 | 19,771
Total accumulated other comprehensive loss |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |
Beginning balance, shareholders' equity | (582) | (669) | (491) | (735)
Other comprehensive loss, net of tax | (28) | (103) | (119) | (37)
Ending balance, shareholders' equity | (610) | (772) | (610) | (772)
Unrealized loss on securities available for sale |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |
Beginning balance, shareholders' equity |  |  | (577) | (739)
AOCI activity before reclassifications |  |  |  | (54)
Amounts reclassified from AOCI to earnings |  |  |  | 12
Other comprehensive loss, net of tax |  |  | (113) | (42)
Ending balance, shareholders' equity | (690) | (781) | (690) | (781)
Unrealized loss on securities available for sale transferred to held to maturity |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |
Beginning balance, shareholders' equity |  |  | (5) | (6)
AOCI activity before reclassifications |  |  |  | 0
Amounts reclassified from AOCI to earnings | 0 | 1 | 0 | 1
Other comprehensive loss, net of tax | 0 | 1 | 0 | 1
Ending balance, shareholders' equity | (5) | (5) | (5) | (5)
Defined benefit pension items |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |
Beginning balance, shareholders' equity |  |  | 91 | 10
AOCI activity before reclassifications |  |  |  | 4
Amounts reclassified from AOCI to earnings |  |  |  | 0
Other comprehensive loss, net of tax | (8) | (4) | (8) | 4
Ending balance, shareholders' equity | 83 | 14 | 83 | 14
Unrealized gain on cash flow hedge derivatives |  |  |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |  |  |
Beginning balance, shareholders' equity |  |  | 0 | 0
AOCI activity before reclassifications |  |  |  | 0
Amounts reclassified from AOCI to earnings |  |  |  | 0
Other comprehensive loss, net of tax | 2 | 0 | 2 | 0
Ending balance, shareholders' equity | $ 2 | $ 0 | $ 2 | $ 0

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