Income Taxes - Carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Carryforwards
Valuation allowance against deferred tax assets	$ 67.0	$ 64.2
U.K.
Carryforwards
Valuation allowance against deferred tax assets	19.5
U.K. | Capital loss carryforwards
Carryforwards
Tax credit carryforwards	4.2
Germany
Carryforwards
Net operating loss carryforwards	45.2
Valuation allowance against net operating loss carryforwards	14.7
New Zealand
Carryforwards
Net operating loss carryforwards	0.4
Italy
Carryforwards
Net operating loss carryforwards	0.1
Federal and state | U.S.
Carryforwards
Net operating loss carryforwards	236.5
Tax credit carryforwards	0.1
Net operating loss carryforwards utilized	271.6
Valuation allowance against net operating loss carryforwards	0.7
Foreign | U.S.
Carryforwards
Tax credit carryforwards	32.0
Valuation allowance against tax credit carryforwards	$ 32.0