Supplemental Cash Flow Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplemental Cash Flow Information [Abstract]
Interest, net of capitalized interest	$ 121.9us-gaap_InterestPaidNet	$ 116.2us-gaap_InterestPaidNet	$ 69.5us-gaap_InterestPaidNet
Income taxes	(0.3)us-gaap_IncomeTaxesPaidNet	1.2us-gaap_IncomeTaxesPaidNet	1.3us-gaap_IncomeTaxesPaidNet
Supplemental Cash Flow [Line Items]
Net cash flows from operating activities	(322.8)	(110.2)	(270.8)
Cash and Cash Equivalents, at Carrying Value	70.2	45.3	227.0	42.0
Supplemental cash flow, noncash investing and financing activities [Abstract]
Capital investments	6.1	10.2	13.9
Variable Interest Entity, Primary Beneficiary [Member] \| SunCoke Middletown [Member]
Supplemental Cash Flow [Line Items]
Net cash flows from operating activities	66.4	82.6	55.2
Cash and Cash Equivalents, at Carrying Value	18.2	14.2
Restricted stock and RSUs [Member]
Supplemental cash flow, noncash investing and financing activities [Abstract]
Issuance of restricted stock and restricted stock units	$ 4.5	$ 3.0	$ 5.4

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

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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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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Amount of cash inflow (outflow) from operating activities, excluding discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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