CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash flows from operating activities:
Net income (loss)	$ 4.4	$ (290.8)
Depreciation	53.7	55.4
Amortization	5.3	7.5
Impairment of Magnetation investment	0.0	256.3
Deferred income taxes	4.5	6.8
Pension and OPEB expense (income)	(11.9)	(16.1)
Contributions to pension trust	0.0	(1.0)
Other postretirement benefit payments	(9.6)	(13.6)
Changes in working capital	71.6	(34.3)
Other operating items, net	18.7	27.1
Net cash flows from operating activities	136.7	(2.7)
Cash flows from investing activities:
Capital investments	(28.8)	(28.3)
Other investing items, net	(0.1)	(5.6)
Net cash flows from investing activities	(28.9)	(33.9)
Cash flows from financing activities:
Net borrowings (payments) under credit facility	(30.0)	75.0
SunCoke Middletown distributions to noncontrolling interest owners	(21.1)	(18.3)
Other financing items, net	(0.3)	(0.9)
Net cash flows from financing activities	(51.4)	55.8
Net increase (decrease) in cash and cash equivalents	56.4	19.2
Cash and cash equivalents, beginning of period	56.6	70.2
Cash and cash equivalents, end of period	113.0	89.4
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Cash flows from operating activities:
Depreciation	50.1	51.8
Variable Interest Entity, Primary Beneficiary [Member] | SunCoke Middletown [Member]
Cash flows from operating activities:
Depreciation	3.6	3.6
Net cash flows from operating activities	20.4	29.0
Cash flows from financing activities:
SunCoke Middletown distributions to noncontrolling interest owners	(21.1)	$ (18.3)
Cash and cash equivalents, beginning of period	7.6
Cash and cash equivalents, end of period	$ 7.0