Derivatives - Classification and fair value of derivatives (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Derivative [Line Items]
Derivative liabilities at fair value	$ 5.0	$ 3.2
Derivatives not designated as hedging instruments | Foreign currency swaps
Derivative [Line Items]
Derivative assets at fair value	0.0	0.0
Derivative liabilities at fair value	0.0	1.7
Notional Value	0.0	40.0
Derivatives not designated as hedging instruments | Foreign currency forwards
Derivative [Line Items]
Derivative assets at fair value	0.5	0.0
Derivative liabilities at fair value	(1.0)	1.3
Notional Value	118.8	83.6
Derivatives not designated as hedging instruments | Foreign currency futures contracts
Derivative [Line Items]
Derivative assets at fair value	0.0	0.2
Derivative liabilities at fair value	0.0	0.0
Notional Value	263.7	133.9
Derivatives not designated as hedging instruments | Weather derivatives
Derivative [Line Items]
Derivative assets at fair value	(2.1)	0.0
Derivative liabilities at fair value	0.0	0.8
Notional Value	9.9	6.2
Derivatives not designated as hedging instruments | Equity warrants
Derivative [Line Items]
Derivative assets at fair value	0.0	0.1
Derivative liabilities at fair value	0.0	0.0
Notional Value	0.0	0.1
Derivatives not designated as hedging instruments | Interest rate cap
Derivative [Line Items]
Derivative assets at fair value	0.0	0.0
Derivative liabilities at fair value	0.0	0.0
Notional Value	$ 0.0	$ 250.0