Investments in Affiliated Companies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Alpha Partners Leasing Limited [Domain]
Equity Method Investment, Summarized Financial Information. Revenue.	$ 93.8	$ 104.0
Equity Method Investment, Summarized Financial Information, Other Expenses	(87.3)	(86.4)
Equity Method Investment, Summarized Financial Information, Gains (Losses)	9.0	22.3
RRPF
Equity Method Investment, Summarized Financial Information, Net Income (Loss)	$ 12.6	$ 32.3