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Investment Securities - Investment in MediaAlpha textual (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2023 | Jun. 30, 2023 | Dec. 31, 2022
Marketing Technology (MediaAlpha) |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |
Tender offer purchase price | $ 5.9 |  |
Purchase price (in dollars per share) | $ 10.00 |  |
Ownership interest (as a percent) | 35.70% | 35.70% | 27.10%
Share price (in usd per share) | $ 10.31 | $ 10.31 |
Investment in MediaAlpha, at fair value | $ 235.7 | $ 235.7 |
Marketing Technology (MediaAlpha) |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |
Investment owned (in shares) | 22.9 | 22.9 |
Fully diluted ownership interest (as a percent) | 33.00% | 33.00% |
Marketing Technology (MediaAlpha) | IPO |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |
Increase in investment owned (in dollars per share) |  | $ 1.00 |
Increase in book value per share (in dollars per share) |  | $ 9.00 |

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