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Accumulated Other Comprehensive (Loss) Income - Schedule of Pretax and After-tax Components of Other Comprehensive Income (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
AOCI activity before reclassification, net amount |  |  | $ (165) | $ (747)
Net realized losses on sales of investment securities available for sale | $ 12 | $ 0 | 26 | 0
Benefit for investment securities available for sale credit losses | (3) | 0 | 0 | 0
Amounts reclassified from AOCI to earnings, Net Amount |  |  | 20 | 8
Other comprehensive loss on securities available for sale, gross amount | (146) | (346) | (197) | (973)
Other comprehensive loss on securities available for sale, gross amount, tax | 38 | 82 | 52 | 234
Other comprehensive loss, net of tax | (108) | (264) | (145) | (739)
Unrealized loss on securities available for sale |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
AOCI activity before reclassification, gross amount | (155) | (348) | (229) | (983)
AOCI activity before reclassification, tax | 40 | 82 | 60 | 236
AOCI activity before reclassification, net amount | (115) | (266) | (169) | (747)
Other comprehensive loss on securities available for sale, gross amount | (146) | (348) | (203) | (983)
Other comprehensive loss on securities available for sale, gross amount, tax | 38 | 82 | 53 | 236
Other comprehensive loss, net of tax | (108) | (266) | (150) | (747)
Unrealized loss on securities available for sale | $12 realized loss on sales of investment securities available for sale, net; $(3) provision for credit losses |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Amounts reclassified from AOCI to earnings, gross amount | 9 | 0 | 26 | 0
Amounts reclassified from AOCI to earnings, tax | (2) | 0 | (7) | 0
Amounts reclassified from AOCI to earnings, Net Amount | 7 | 0 | 19 | 0
Unrealized loss on securities available for sale transferred to held to maturity |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
AOCI activity before reclassification, gross amount | 0 | 0 | 0 | 0
AOCI activity before reclassification, tax | 0 | 0 | 0 | 0
AOCI activity before reclassification, net amount | 0 | 0 | 0 | 0
Amounts reclassified from AOCI to earnings, Net Amount |  |  | 1 | 1
Other comprehensive loss on securities available for sale, gross amount | 0 | 0 | 1 | 1
Other comprehensive loss on securities available for sale, gross amount, tax | 0 | 0 | 0 | 0
Other comprehensive loss, net of tax | 0 | 0 | 1 | 1
Unrealized loss on securities available for sale transferred to held to maturity | Interest on investment securities |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Amounts reclassified from AOCI to earnings, gross amount | 0 | 0 | 1 | 1
Amounts reclassified from AOCI to earnings, tax | 0 | 0 | 0 | 0
Amounts reclassified from AOCI to earnings, Net Amount | 0 | 0 | 1 | 1
Defined benefit pension items |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
AOCI activity before reclassification, gross amount | 0 | 0 | 5 | 0
AOCI activity before reclassification, tax | 0 | 0 | (1) | 0
AOCI activity before reclassification, net amount | 0 | 0 | 4 | 0
Amounts reclassified from AOCI to earnings, Net Amount |  |  | 0 | 7
Other comprehensive loss on securities available for sale, gross amount | 0 | 2 | 5 | 9
Other comprehensive loss on securities available for sale, gross amount, tax | 0 | 0 | (1) | (2)
Other comprehensive loss, net of tax | 0 | 2 | 4 | 7
Defined benefit pension items | Other noninterest expense |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |
Amounts reclassified from AOCI to earnings, gross amount | 0 | 2 | 0 | 9
Amounts reclassified from AOCI to earnings, tax | 0 | 0 | 0 | (2)
Amounts reclassified from AOCI to earnings, Net Amount | $ 0 | $ 2 | $ 0 | $ 7

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