Supplemental Cash Flow Information (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Cash Flow Elements [Abstract]
Payments of interest and commitment fees	$ 74.8us-gaap_InterestPaid	$ 49.7us-gaap_InterestPaid	$ 41.5us-gaap_InterestPaid
Capitalized interest	13.8us-gaap_InterestPaidCapitalized	13.3us-gaap_InterestPaidCapitalized	3.9us-gaap_InterestPaidCapitalized
Cash paid for income taxes	0.8us-gaap_IncomeTaxesPaidNet	(0.6)us-gaap_IncomeTaxesPaidNet	(0.3)us-gaap_IncomeTaxesPaidNet
Incurred liabilities for fixed and intangible asset additions	61.2	52.5	14.1
Other Asset Additions Incurred but Not yet Paid	$ 9.4	$ 0.1

Other Asset Additions Incurred but Not yet Paid

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- Definition

Future cash outflow to pay for purchases of fixed assets that have occurred.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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- Definition

The amount of cash paid for interest during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

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-Publisher FASB

-Name Accounting Standards Codification

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-Paragraph 25

-Subparagraph (e)

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