CONDENSED CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Investments and receivables at fair value	$ 3,054.5	$ 2,907.7
Class A
Common stock, nominal value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued (in shares)	173,785,920	173,046,371
Common stock, outstanding (in shares)	173,785,920	173,046,371
Class B
Common stock, nominal value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued (in shares)	12,968,658	12,968,658
Common stock, outstanding (in shares)	12,968,658	12,968,658
Class C
Common stock, nominal value (in dollars per share)	$ 0.01	$ 0.01
Common stock, issued (in shares)	160,343,481	162,710,787
Common stock, outstanding (in shares)	160,343,481	162,710,787