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Accumulated Other Comprehensive Income (Loss) - Schedule of Pretax and After-tax Components of Other Comprehensive Income (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2022 | Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Amounts reclassified from AOCI | $ 3 | $ (2)
AOCI activity before reclassification, net amount | (318) | (44)
Gross Unrealized | (415) | (59)
Income Taxes | 100 | 13
Other comprehensive loss, net of tax | (315) | (46)
Defined benefit pension items |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Amounts reclassified from AOCI | 2 | 5
AOCI activity before reclassification, net amount | 0 | 0
Gross Unrealized | 3 | 7
Income Taxes | (1) | (2)
Other comprehensive loss, net of tax | 2 | 5
Defined benefit pension items | Other noninterest expense |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Reclassification out of AOCI, gross amount | 3 | 7
Reclassification out of AOCI, tax | (1) | (2)
Amounts reclassified from AOCI | 2 | 5
Unrealized (losses) gains on securities available for sale |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
AOCI activity before reclassification, gross amount | (419) | (57)
AOCI activity before reclassification, tax | 101 | 13
AOCI activity before reclassification, net amount | (318) | (44)
Gross Unrealized | (418) | (66)
Income Taxes | 101 | 15
Other comprehensive loss, net of tax | (317) | (51)
Unrealized (losses) gains on securities available for sale | Realized gains on investment securities available for sale, net |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |
Reclassification out of AOCI, gross amount | 1 | (9)
Reclassification out of AOCI, tax | 0 | 2
Amounts reclassified from AOCI | $ 1 | $ (7)

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