Equity-Method Eligible Investments (Details)	Dec. 31, 2019	May 31, 2019	Dec. 31, 2018
DavidShield & PassportCard
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	50.00%		50.00%
MediaAlpha
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	48.30%
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)	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%		12.30%
Kudu
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)			49.50%
Minimum | Tuckerman Capital Fund III, L.P.
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	17.50%		18.50%
Minimum | Enlightenment Capital Funds
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	10.00%		10.30%
Minimum | Kudu Investments
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	3.20%
Maximum | Tuckerman Capital Fund III, L.P.
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	62.40%		62.30%
Maximum | Enlightenment Capital Funds
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	38.40%		36.50%
Maximum | Kudu Investments
Investments in and Advances to Affiliates [Line Items]
Ownership interest (as a percent)	30.00%