Income Taxes - Carryforwards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Operating loss carryforwards
Valuation allowance against deferred tax assets	$ 17.2	$ 17.3
UK
Operating loss carryforwards
Amount of tax credit carryforwards not subject to expiration	4.7
Valuation allowance against deferred tax assets	6.5
German
Operating loss carryforwards
Net operating loss carryforwards not subject to expiration	20.1
Valuation allowance against net operating loss carryforwards	7.3
Australia
Operating loss carryforwards
Net operating loss carryforwards not subject to expiration	22.1
Australia | Capital loss carryforwards
Operating loss carryforwards
Valuation allowance against tax credit carryforwards	0.1
Italian
Operating loss carryforwards
Net operating loss carryforwards not subject to expiration	0.1
Canada
Operating loss carryforwards
Net operating loss carryforwards not subject to expiration	1.7
Valuation allowance against net operating loss carryforwards	0.4
State
Operating loss carryforwards
Net operating loss carryforwards that expire at various dates	240.1
Net operating loss carryforwards utilized	174.2
Valuation allowance against net operating loss carryforwards	2.6
Valuation allowance against tax credit carryforwards	0.3
Federal and state
Operating loss carryforwards
Amount of tax credit carryforwards not subject to expiration	$ 8.5