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Income Taxes (Net Operating and Capital Loss Carryforwards) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net deferred tax assets
Total net deferred income tax assets	$ 215.0	$ 207.6
Change in valuation allowance	18.7	36.0	$ 49.9
Alternative minimum tax credit carryforwards, not subject to expiration	1.9
Tax credit carryforwards	16.9	13.4
UNITED STATES
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	22.6
Net deferred tax assets
Foreign tax credit carryforwards, subject to expiration	0.4
Tax credit carryforwards	14.6
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	662.3
Net deferred tax assets
Gross deferred tax asset	220.5
Valuation allowance	(155.1)
Total net deferred income tax assets	65.4
Operating and Capital Loss Carryforward | UNITED STATES
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	543.4
Net deferred tax assets
Gross deferred tax asset	186.6
Valuation allowance	(121.2)
Total net deferred income tax assets	65.4
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	96.8
Net deferred tax assets
Gross deferred tax asset	28.3
Valuation allowance	(28.3)
Total net deferred income tax assets	0.0
Operating and Capital Loss Carryforward | Foreign Tax Authority [Member]
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	21.8
Net deferred tax assets
Gross deferred tax asset	5.5
Valuation allowance	(5.5)
Total net deferred income tax assets	0.0
Operating and Capital Loss Carryforward | NETHERLANDS
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	0.3
Net deferred tax assets
Gross deferred tax asset	0.1
Valuation allowance	(0.1)
Total net deferred income tax assets	0.0
No expiration date [Member] | 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	118.6
No expiration date [Member] | Operating and Capital Loss Carryforward | UNITED 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 [Member] | 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	96.8
No expiration date [Member] | Operating and Capital Loss Carryforward | Foreign Tax Authority [Member]
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	21.8
No expiration date [Member] | Operating and Capital Loss Carryforward | NETHERLANDS
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	0.0
2026-2035 | 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	540.6
2026-2035 | Operating and Capital Loss Carryforward | UNITED STATES
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	540.6
2026-2035 | 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
2026-2035 | Operating and Capital Loss Carryforward | Foreign Tax Authority [Member]
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	0.0
2026-2035 | Operating and Capital Loss Carryforward | NETHERLANDS
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	0.0
2021-2025 | 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	2.3
2021-2025 | Operating and Capital Loss Carryforward | UNITED STATES
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	2.0
2021-2025 | 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
2021-2025 | Operating and Capital Loss Carryforward | Foreign Tax Authority [Member]
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	0.0
2021-2025 | Operating and Capital Loss Carryforward | NETHERLANDS
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	0.3
2016-2020 | 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	0.8
2016-2020 | Operating and Capital Loss Carryforward | UNITED STATES
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	0.8
2016-2020 | 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
2016-2020 | Operating and Capital Loss Carryforward | Foreign Tax Authority [Member]
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	0.0
2016-2020 | Operating and Capital Loss Carryforward | NETHERLANDS
Summary of net operating loss and capital loss carryforwards, the expiration dates and the deferred tax assets thereon
Operating Loss Carryforwards	0.0
Star & Shield Insurance Exchange [Member]
Net deferred tax assets
Change in valuation allowance	$ (1.2)	$ (3.2)

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Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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