Investments - Summary of equity securities and other long-term investments (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Investments, Debt and Equity Securities [Abstract]
Equity securities, Cost or amortized cost	$ 4.5
Equity securities, Gross unrealized gains	0.1
Equity securities, Gross unrealized losses	(2.0)
Equity securities, Net foreign currency gains	0.2
Equity securities, Fair value	2.8	$ 0.0
Other long-term investments, Cost or amortized cost	443.0	4.0
Other long-term investments, Gross unrealized gains	28.9	0.0
Other long-term investments, Gross unrealized losses	(16.8)	0.0
Other long-term investments, net foreign currency gains	1.0	0.0
Other long-term investments, Fair value	$ 456.1	$ 4.0