Investment Securities - Investment in MediaAlpha textual (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2023	Dec. 31, 2022
Marketing Technology (MediaAlpha)
Subsidiary, Sale of Stock [Line Items]
Ownership interest (as a percent)	26.80%	27.10%
Share price (in usd per share)	$ 14.98
Investment in MediaAlpha, at fair value	$ 253.8
Marketing Technology (MediaAlpha)
Subsidiary, Sale of Stock [Line Items]
Investment owned (in shares)	16.9
Fully diluted ownership interest (as a percent)	24.30%
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)	$ 6.60

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Balance held at close of period in number of shares.

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Price of a single share of a number of saleable stocks of a company.

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Equity Method Investment, Fully Diluted Ownership Percentage

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Investment Owned, Increase (Decrease) in Value, Book Value Per Share

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Investment Owned, Increase (Decrease) in Value, Per Share

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