Taxation (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Effective Income Tax Rate Reconciliation
Effective rate of tax	11.00%	20.00%	(5.00%)	21.00%
Net tax credit following the settlement of certain tax position with the Canadian revenue authorities	$ 27.7		$ 243.7
Decreases resulting from settlements with the taxing authorities	(26.5)		(291.7)
Future decrease in the unrecognized tax benefit.	20.0		20.0
Interest income in respect of cash deposited with Canadian revenue authorities	$ 2.8		$ 21.4

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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-Publisher FASB

-Name Accounting Standards Codification

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Includes all other interest income, net of discount accretion and premium amortization, and dividend income. It may include dividend income from equity securities that do not have readily determinable fair values that are reportable in Other Assets, and interest income on interest-only strips receivable (not in the form of a security) that are included in Other Assets.

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-Subparagraph (SX 210.9-04.4)

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The amount of the unrecognized tax benefit of a position taken for which it is reasonably possible that the total amount thereof will significantly increase or decrease within twelve months of the balance sheet date.

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Amount of increase (decrease) to previously recorded tax expense. Includes, but is not limited to, significant settlements of income tax disputes, and unusual tax positions or infrequent actions taken by the entity, including tax assessment reversal, and IRS tax settlement.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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