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Stockholders' Equity - Narrative (Details) $ / shares in Units, $ in Millions |  | 9 Months Ended |
--- | --- | --- | ---
Jan. 03, 2022 | Sep. 30, 2022 shares | Mar. 12, 2020 USD ($) $ / shares shares
Class of Stock [Line Items] |  |  |
Depositary shares, shares issued (in shares) |  |  | 13,800,000
Depository Shares, percentage of preferred stock |  |  | 0.025
Depository shares, equivalent value per preferred share | $ / shares |  |  | $ 1,000
Depositary shares, shares issued, value | $ |  |  | $ 345
CIT Group Inc. |  |  |
Class of Stock [Line Items] |  |  |
Common stock issuance - CIT Merger (in shares) |  | 6,100,000 |
Class A Common Stock |  |  |
Class of Stock [Line Items] |  |  |
Common stock, voting right per share |  | 1 |
Common stock issuance - CIT Merger (in shares) |  | 6,140,010 |
Class A Common Stock | CIT Group Inc. |  |  |
Class of Stock [Line Items] |  |  |
Common stock, terms of conversion, conversion ratio | 0.062 |  |
Class B Common Stock |  |  |
Class of Stock [Line Items] |  |  |
Common stock, voting right per share |  | 16 |
Common stock issuance - CIT Merger (in shares) |  | 0 |
Depositary Shares, Each Representing a 1/40th Interest in a Share of 5.375% Non-Cumulative Perpetual Preferred Stock, Series A |  |  |
Class of Stock [Line Items] |  |  |
Dividend |  | 5.375% |
Series B Preferred Stock |  |  |
Class of Stock [Line Items] |  |  |
Dividend |  | 5.80% |
Series B Preferred Stock | CIT Group Inc. |  |  |
Class of Stock [Line Items] |  |  |
Dividend | 5.625% |  |
Common stock, terms of conversion, conversion ratio | 1 |  |
Series C Preferred Stock |  |  |
Class of Stock [Line Items] |  |  |
Dividend |  | 5.625% |
Series C Preferred Stock | CIT Group Inc. |  |  |
Class of Stock [Line Items] |  |  |
Common stock, terms of conversion, conversion ratio | 1 |  |

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