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Business Combinations - Schedule of Business Acquisition, Pro Forma Information (Details) - CIT Group Inc. - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021
Business Acquisition [Line Items] |  |  |  |
Business acquisition, pro forma net income (loss) | $ 282 | $ 355 | $ 617 | $ 772
Interest income |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Business acquisition, pro forma revenue | 758 | 712 | 1,468 | 1,438
Noninterest income |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Business acquisition, pro forma revenue | $ 425 | $ 498 | $ 843 | $ 1,499

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