Investments - Summary of equity securities and other long-term investments (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Investments, Debt and Equity Securities [Abstract]
Equity securities, Cost or amortized cost	$ 1.8	$ 4.5
Equity securities, Gross unrealized gains	0.0	0.1
Equity securities, Gross unrealized losses	(0.2)	(2.0)
Equity securities, Net foreign currency gains	0.0	0.2
Equity securities, Fair value	1.6	2.8
Other long-term investments, Cost or amortized cost	392.0	443.0
Other long-term investments, Gross unrealized gains	27.5	28.9
Other long-term investments, Gross unrealized losses	(41.8)	(16.8)
Other long-term investments, net foreign currency gains	(0.5)	1.0
Other long-term investments, Fair value	$ 377.2	$ 456.1