Investment Securities - Investment in MediaAlpha (Details) - MediaAlpha - USD ($) $ / shares in Units, $ in Millions	Oct. 30, 2020	Dec. 31, 2020
Investment securities
Investment owned (in shares)	20,532,202
Ownership interest (as a percent)	35.00%
Fully diluted ownership interest (as a percent)	32.30%
Share price (in USD per share)		$ 39.07
Value of investment		$ 802.2
IPO
Investment securities
Sale of stock, number of shares issued in transaction (in shares)	3,609,894
Sale of stock, consideration received in transaction	$ 63.8

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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