Equity-Method Eligible Investments - Carrying Values of Investments (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
MediaAlpha
Schedule of Equity Method Investments [Line Items]
Investment in MediaAlpha, at fair value	$ 802.2	$ 180.0
Other unconsolidated investments
Schedule of Equity Method Investments [Line Items]
Investment in MediaAlpha, at fair value	$ 698.1	$ 581.7

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
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-Section 50
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
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Balance Type:	debit
Period Type:	instant