Income Taxes (Deferred Tax Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Net operating loss carryforwards	$ 117.9	$ 98.3
Pension and retiree benefits accruals	44.7	33.0
Inventory	9.3us-gaap_DeferredTaxAssetsInventory	12.8us-gaap_DeferredTaxAssetsInventory
Depreciation and fixed assets	13.6	12.0
Tax credit carryforwards	9.8	9.3
Other liabilities	72.3bgc_DeferredTaxAssetsOtherLiabilities	67.7bgc_DeferredTaxAssetsOtherLiabilities
Valuation allowance	(145.4)	(93.8)
Total deferred tax assets	122.2us-gaap_DeferredTaxAssetsNet	139.3us-gaap_DeferredTaxAssetsNet
Deferred tax liabilities:
Convertible debt discount	186.2	165.7
Inventory	1.8bgc_DeferredTaxLiabilitiesInventory	1.2bgc_DeferredTaxLiabilitiesInventory
Depreciation and fixed assets	43.2	87.4
Intangibles	13.5	42.8
Other	12.2us-gaap_DeferredTaxLiabilitiesOther	11.0us-gaap_DeferredTaxLiabilitiesOther
Total deferred tax liabilities	256.9us-gaap_DeferredTaxLiabilities	308.1us-gaap_DeferredTaxLiabilities
Net deferred tax assets (liabilities)	$ (134.7)us-gaap_DeferredTaxAssetsLiabilitiesNet	$ (168.8)us-gaap_DeferredTaxAssetsLiabilitiesNet

Deferred Tax Assets, Other Liabilities

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The tax effect as of the balance sheet date of the amount of future tax deductions arising from all unused tax credit carryforwards which have been reduced by a valuation allowance.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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Amount of deferred tax liability attributable to taxable temporary differences from intangible assets other than goodwill.

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