Investments in Affiliated Companies (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Alpha Partners Leasing Limited [Domain]
Equity Method Investment, Summarized Financial Information. Revenue.	$ 91.1	$ 112.5	$ 277.3	$ 318.5
Equity Method Investment, Summarized Financial Information, Other Expenses	(91.9)	(95.9)	(267.4)	(271.0)
Equity Method Investment, Summarized Financial Information, Gains (Losses)	7.7	10.0	36.2	48.2
RRPF
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	$ 5.5	$ 21.7	$ 37.2	$ 77.6