Income Taxes (Net Operating and Capital Loss Carryforwards) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Net deferred tax assets
Total net deferred income tax assets	$ 27.5	$ 32.7
Alternative minimum tax credit carryforwards, not subject to expiration	1.3
Unites States
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	3.1
Operating and Capital Loss Carryforward
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	471.4
Net deferred tax assets
Gross deferred tax asset	106.9
Valuation allowance	(106.9)
Total net deferred income tax assets	0.0
Operating and Capital Loss Carryforward | Unites States
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	332.3
Net deferred tax assets
Gross deferred tax asset	73.0
Valuation allowance	(73.0)
Total net deferred income tax assets	0.0
Operating and Capital Loss Carryforward | Luxembourg
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	77.7
Net deferred tax assets
Gross deferred tax asset	20.2
Valuation allowance	(20.2)
Total net deferred income tax assets	0.0
Operating and Capital Loss Carryforward | United Kingdom
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	6.7
Net deferred tax assets
Gross deferred tax asset	1.1
Valuation allowance	(1.1)
Total net deferred income tax assets	0.0
Operating and Capital Loss Carryforward | Israel
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	54.7
Net deferred tax assets
Gross deferred tax asset	12.6
Valuation allowance	(12.6)
Total net deferred income tax assets	0.0
2018-2022 | Operating and Capital Loss Carryforward
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.3
2018-2022 | Operating and Capital Loss Carryforward | Unites States
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.3
2018-2022 | Operating and Capital Loss Carryforward | Luxembourg
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
2018-2022 | Operating and Capital Loss Carryforward | United Kingdom
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
2018-2022 | Operating and Capital Loss Carryforward | Israel
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
2023-2027 | Operating and Capital Loss Carryforward
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
2023-2027 | Operating and Capital Loss Carryforward | Unites States
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
2023-2027 | Operating and Capital Loss Carryforward | Luxembourg
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
2023-2027 | Operating and Capital Loss Carryforward | United Kingdom
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
2023-2027 | Operating and Capital Loss Carryforward | Israel
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
2028-2037 | Operating and Capital Loss Carryforward
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	378.4
2028-2037 | Operating and Capital Loss Carryforward | Unites States
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	332.0
2028-2037 | Operating and Capital Loss Carryforward | Luxembourg
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	46.4
2028-2037 | Operating and Capital Loss Carryforward | United Kingdom
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
2028-2037 | Operating and Capital Loss Carryforward | Israel
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
No expiration date | Operating and Capital Loss Carryforward
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	92.7
No expiration date | Operating and Capital Loss Carryforward | Unites States
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	0.0
No expiration date | Operating and Capital Loss Carryforward | Luxembourg
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	31.3
No expiration date | Operating and Capital Loss Carryforward | United Kingdom
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	6.7
No expiration date | Operating and Capital Loss Carryforward | Israel
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	54.7
2030 | Operating and Capital Loss Carryforward
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating loss carryforwards	$ (6.7)