CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Cash flows from operating activities:
Net income (loss)	$ 6.8	$ (6.9)
Depreciation	48.6	48.3
Amortization	5.9	6.3
Deferred income taxes	(4.4)	(9.4)
Pension and OPEB expense (income)	(15.9)	(8.5)
Contributions to pension trust	(30.0)	(28.7)
Other postretirement benefit payments	(18.1)	(16.3)
Other operating items, net	6.4	8.0
Net cash flows from operating activities	(7.0)	(150.0)
Cash flows from investing activities:
Capital investments	(16.5)	(29.7)
Other investing items, net	0.8	(0.2)
Net cash flows from investing activities	(15.7)	(29.9)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility	0	(105.0)
Proceeds from issuance of long-term debt	0	373.3
Redemption of long-term debt	(0.2)	(73.5)
Debt issuance costs	(1.5)	(8.2)
Purchase of treasury stock	(0.6)	(1.7)
Common stock dividends paid	0	(5.5)
Other financing items, net	(1.1)	0.8
Net cash flows from financing activities	(12.5)	180.2
Net increase (decrease) in cash and cash equivalents	(35.2)	0.3
Cash and cash equivalents, beginning of period	227.0	42.0
Cash and cash equivalents, end of period	191.8	42.3
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Cash flows from operating activities:
Depreciation	45.1	44.9
Changes in working capital	(9.6)	(150.7)
Cash flows from investing activities:
Capital investments	(15.5)	(10.5)
SunCoke Middletown [Member]
Cash flows from operating activities:
Depreciation	3.5	3.4
Changes in working capital	3.3	7.9
Cash flows from investing activities:
Capital investments	(1.0)	(19.2)
Cash flows from financing activities:
SunCoke Middletown distributions to noncontrolling interest owners	$ (9.1)	$ 0