CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income (loss)	$ (34.1)	$ 17.4	$ (998.6)
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	201.9	190.1	192.0
Amortization	20.4	19.1	17.0
Deferred income taxes	8.2	(7.3)	771.2
Income taxes of noncontrolling interests	0	0	17.6
Contributions to pension trust	(196.5)	(181.1)	(170.2)
Pension and OPEB expense (income)	(92.5)	(68.6)	(35.3)
Pension corridor charges	2.0	0	157.3
Other operating items, net	15.8	9.4	(1.9)
Change in assets and liabilities, net of effect of acquired business:
Other assets	(8.2)	(4.7)	(4.2)
Pension obligations	(18.2)	(10.0)	(6.7)
Postretirement benefit obligations	(63.9)	(63.4)	(64.1)
Other liabilities	9.8	0.5	0.4
Net cash flows from operating activities	(322.8)	(110.2)	(270.8)
Cash flows from investing activities:
Capital investments	(81.1)	(63.6)	(64.1)
Investments in Magnetation LLC and AK Coal	(100.0)	(50.0)	(60.6)
Investments in acquired business, net of cash acquired	(690.3)	0	0
Other investing items, net	13.6	15.1	6.1
Net cash flows from investing activities	(857.8)	(98.5)	(118.6)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility	515.0	90.0	(250.0)
Proceeds from issuance of long-term debt	427.1	31.9	873.3
Redemption of long-term debt	(0.8)	(27.4)	(74.0)
Proceeds from issuance of common stock	345.3	0	96.4
Debt issuance costs	(15.5)	(3.4)	(22.3)
Common stock dividends paid	0	0	(11.0)
SunCoke Middletown distributions to noncontrolling interest owners	(61.0)	(64.8)	(36.6)
Other financing items, net	(4.6)	0.7	(1.4)
Net cash flows from financing activities	1,205.5	27.0	574.4
Net increase (decrease) in cash and cash equivalents	24.9	(181.7)	185.0
Cash and cash equivalents, beginning of year	45.3	227.0	42.0
Cash and cash equivalents, end of year	70.2	45.3	227.0
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)	(30.8)	(31.7)
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	187.6	176.1	178.4
Change in assets and liabilities, net of effect of acquired business:
Accounts receivable	34.4	(51.1)	94.2
Inventories	(215.9)	16.4	(182.8)
Accounts payable and other current liabilities	28.5	48.7	(20.6)
Cash flows from investing activities:
Capital investments	(79.7)	(60.0)	(45.5)
SunCoke Middletown [Member]
Adjustments to reconcile net income (loss) to cash flows from operating activities:
Depreciation	14.3	14.0	13.6
Change in assets and liabilities, net of effect of acquired business:
Accounts receivable	(0.6)	1.0	0.3
Inventories	(7.5)	6.2	(4.5)
Accounts payable and other current liabilities	(3.3)	(2.0)	(0.2)
Cash flows from investing activities:
Capital investments	(1.4)	(3.6)	(18.6)
Cash flows from financing activities:
SunCoke Middletown distributions to noncontrolling interest owners	$ (61.0)	$ (64.8)	$ (36.6)