Income Tax Expense - Carryforwards (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Net operating loss ("NOL") carry forwards
Federal net operating loss carry forwards	$ 279.3
State net operating loss carry forwards	57.0
Foreign net operating loss carry forwards	67.0
Operating operating loss carryforward	67.0us-gaap_OperatingLossCarryforwards
Period for which foreign NOL can be carried forward (in years)	10 years
Equity impact when deferred tax assets are realized	8.4
Tax credit carry forwards
Foreign tax credit carry forwards	17.2
Research and development tax credit carry forwards	18.8
Alternative minimum tax credit carry forwards	2.1
State tax credits carry forward	$ 2.3

Deferred Tax Asset, Equity Impact When Realized

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The tax effect as of the balance sheet date of the amount of state tax effects arising from unused foreign tax credit carryforwards which will decrease future taxable income if applied in future years; a tax credit carryforward is the amount by which tax credits available for utilization exceeded statutory limits on inclusion in historical filings, and which can only be utilized if sufficient tax-basis income is generated in future periods and providing tax laws continue to allow such utilization.

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Operating Loss Carryforwards Period Minimum

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible domestic operating loss carryforwards. Excludes state and local operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards.

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Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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