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Equity-Method Eligible Investments - Ownership Percentages (Details)	Dec. 31, 2020	May 07, 2020	May 06, 2020	Dec. 31, 2019	May 31, 2019	Feb. 26, 2019	Feb. 25, 2019
DavidShield & PassportCard
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	53.80%	53.80%	50.00%	50.00%
MediaAlpha
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	35.00%			48.30%
MediaAlpha | Minimum
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)						48.30%
MediaAlpha | Maximum
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)							61.00%
durchblicker
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	45.00%			45.00%
Elementum Holdings, L.P.
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	28.90%			30.00%	30.00%
Compare.com
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	18.40%			18.40%
JAM Partners L.P.
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)				11.10%
Enlightenment Capital Funds | Minimum
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	9.70%			10.00%
Enlightenment Capital Funds | Maximum
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	66.70%			38.40%
Tuckerman Capital Funds | Minimum
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	14.90%			17.50%
Tuckerman Capital Funds | Maximum
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	62.00%			62.40%
Kudu Investments | Minimum
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	3.20%			3.20%
Kudu Investments | Maximum
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	35.00%			30.00%
New Market Solutions, LLC
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	46.70%

X

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

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- Definition

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+ References

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