CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income (loss)	$ (446.2)	$ (34.1)	$ 17.4
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	216.0	201.9	190.1
Amortization	21.2	20.4	19.1
Impairment of Magnetation and AFSG investments	297.9	0.0	0.0
Deferred income taxes	62.1	8.2	(7.3)
Contributions to pension trust	(24.1)	(196.5)	(181.1)
Pension and OPEB expense (income)	(63.0)	(92.5)	(68.6)
Pension and OPEB net corridor charge	131.2	2.0	0.0
Affiliate (earnings) losses and distributions,net	19.7	9.8	11.3
Other operating items, net	(4.4)	6.0	(1.9)
Change in assets and liabilities, net of effect of acquired business:
Accounts receivable	228.1	33.8	(50.1)
Inventories	(53.8)	(223.4)	22.6
Accounts payable and other current liabilities	(139.7)	25.2	46.7
Charge for facility idling	28.1	0.0	0.0
Other assets	(7.6)	(8.2)	(4.7)
Pension obligations	(12.7)	(18.2)	(10.0)
Postretirement benefit obligations	(48.3)	(63.9)	(63.4)
Other liabilities	(1.1)	9.8	0.5
Net cash flows from operating activities	200.3	(322.8)	(110.2)
Cash flows from investing activities:
Capital investments	(99.0)	(81.1)	(63.6)
Investments in Magnetation LLC	0.0	(100.0)	(50.0)
Investments in acquired business, net of cash acquired	0.0	(690.3)	0.0
Proceeds from sale of equity investee	25.0	0.0	0.0
Proceeds from AFSG Holdings, Inc. distribution	14.0	0.0	0.0
Other investing items, net	12.5	13.6	15.1
Net cash flows from investing activities	(47.5)	(857.8)	(98.5)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility	(55.0)	515.0	90.0
Proceeds from issuance of long-term debt	0.0	427.1	31.9
Redemption of long-term debt	(14.1)	(0.8)	(27.4)
Proceeds from issuance of common stock	0.0	345.3	0.0
Debt issuance costs	0.0	(15.5)	(3.4)
SunCoke Middletown distributions to noncontrolling interest owners	(96.3)	(61.0)	(64.8)
Other financing items, net	(1.0)	(4.6)	0.7
Net cash flows from financing activities	(166.4)	1,205.5	27.0
Net increase (decrease) in cash and cash equivalents	(13.6)	24.9	(181.7)
Cash and cash equivalents, beginning of year	70.2	45.3	227.0
Cash and cash equivalents, end of year	56.6	70.2	45.3
Butler and Zanesville Works Retiree Healthcare Benefits Litigation [Member]
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Contributions to retirees VEBAs	(3.1)	(3.1)	(30.8)
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	201.7	187.6	176.1
SunCoke Middletown [Member]
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	14.3	14.3	14.0
Cash flows from financing activities:
SunCoke Middletown distributions to noncontrolling interest owners	$ (96.3)	$ (61.0)	$ (64.8)