Equity-Method Eligible Investments - Equity Method Investments Financial Data (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Total assets	$ 7,660.9		$ 7,660.9		$ 7,000.7
Total liabilities	4,168.9		4,168.9		3,296.0
Total revenues	76.7	$ 342.4	337.1	$ 445.8
Net income (loss)	(169.2)	138.5	(135.8)	63.2
Marketing Technology (MediaAlpha)
Schedule of Equity Method Investments [Line Items]
Total assets	285.9		285.9		289.8
Total liabilities	345.4		345.4		$ 351.4
Total revenues	103.4	157.4	246.0	330.9
Total expenses	116.4	157.8	268.9	331.1
Net income (loss)	$ (13.0)	$ (0.4)	$ (22.9)	$ (0.2)