Supplementary Guarantor Information (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
	Sep. 16, 2014	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Statements of Operations [Abstract]
Net sales		$ 1,542.7	$ 1,709.9	$ 1,689.4	$ 1,750.9	$ 1,997.6	$ 1,593.8	$ 1,530.8	$ 1,383.5	$ 6,692.9	$ 6,505.7	$ 5,570.4
Cost of products sold (exclusive of items shown separately below)										6,032.0	6,007.7	5,107.8
Selling and administrative expenses (exclusive of items shown separately below)										261.9	247.2	205.3
Depreciation										216.0	201.9	190.1
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										(63.0)	(92.5)	(68.6)
Pension and OPEB net corridor charge										131.2	2.0	0.0
Charge for facility idling										28.1	0.0	0.0
Total operating costs										6,606.2	6,366.3	5,434.6
Operating profit (loss)		(34.4)	80.2	7.1	33.8	74.5	63.7	36.5	(35.3)	86.7	139.4	135.8
Interest expense										173.0	144.7	127.4
Impairment of Magnetation investment					(256.3)					(256.3)	0.0	0.0
Impairment of AFSG investment										(41.6)	0.0	0.0
Other income (expense)										1.4	(21.1)	(1.4)
Income (loss) before income taxes										(382.8)	(26.4)	7.0
Income tax expense (benefit)										63.4	7.7	(10.4)
Equity in net income (loss) of subsidiaries										0.0	0.0	0.0
Net income (loss)										(446.2)	(34.1)	17.4
Less: Net income attributable to noncontrolling interests										62.8	62.8	64.2
Net income (loss) attributable to AK Steel Holding Corporation		(145.4)	$ 6.7	$ (64.0)	(306.3)	13.5	$ (7.2)	$ (17.1)	(86.1)	(509.0)	(96.9)	(46.8)
Other comprehensive income (loss)										17.2	(527.8)	322.3
Comprehensive income (loss) attributable to AK Steel Holding Corporation										(491.8)	(624.7)	275.5
Current assets:
Cash and cash equivalents		56.6			70.2	70.2			45.3	70.2	45.3	227.0	$ 56.6	$ 70.2	$ 45.3	$ 227.0
Accounts receivable, net													444.9	644.3
Inventory, net													1,226.3	1,172.1
Other current assets													78.4	71.4
Total current assets													1,806.2	1,958.0
Property, plant and equipment													6,466.0	6,388.4
Accumulated depreciation													(4,379.5)	(4,175.2)
Property, plant and equipment, net													2,086.5	2,213.2
Other non-current assets:
Investments in affiliates													70.7	388.7
Investment in subsidiaries													0.0	0.0
Inter-company accounts													0.0	0.0
Other non-current assets													121.0	268.1
TOTAL ASSETS													4,084.4	4,828.0
Current liabilities:
Accounts payable													703.4	803.1
Accrued liabilities													261.5	266.5
Current portion of pension and other postretirement benefit obligations													77.7	55.6
Total current liabilities													1,042.6	1,125.2
Non-current liabilities:
Long-term debt													2,354.1	2,422.0
Pension and other postretirement benefit obligations													1,146.9	1,225.3
Other non-current liabilities													136.4	132.5
TOTAL LIABILITIES													4,680.0	4,905.0
Equity (deficit):
Total stockholders' equity (deficit)													(977.6)	(492.5)
Noncontrolling interests													382.0	415.5
TOTAL EQUITY (DEFICIT)													(595.6)	(77.0)	192.7	(91.0)
TOTAL LIABILITIES AND EQUITY (DEFICIT)													4,084.4	4,828.0
Condensed Cash Flows [Abstract]
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 joint venture										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	$ 345.3									0.0	345.3	0.0
Debt issuance costs										0.0	(15.5)	(3.4)
Inter-company activity										0.0	0.0	0.0
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	70.2	45.3	227.0
Cash and cash equivalents, end of year		56.6				70.2				56.6	70.2	45.3
AK Holding [Member]
Condensed Statements of Operations [Abstract]
Net sales										0.0	0.0	0.0
Cost of products sold (exclusive of items shown separately below)										0.0	0.0	0.0
Selling and administrative expenses (exclusive of items shown separately below)										4.9	4.6	4.4
Depreciation										0.0	0.0	0.0
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										0.0	0.0	0.0
Pension and OPEB net corridor charge										0.0	0.0
Charge for facility idling										0.0
Total operating costs										4.9	4.6	4.4
Operating profit (loss)										(4.9)	(4.6)	(4.4)
Interest expense										0.0	0.0	0.0
Impairment of Magnetation investment										0.0
Impairment of AFSG investment										0.0
Other income (expense)										0.0	0.0	0.0
Income (loss) before income taxes										(4.9)	(4.6)	(4.4)
Income tax expense (benefit)										0.0	0.0	0.0
Equity in net income (loss) of subsidiaries										(504.1)	(92.3)	(42.4)
Net income (loss)										(509.0)	(96.9)	(46.8)
Less: Net income attributable to noncontrolling interests										0.0	0.0	0.0
Net income (loss) attributable to AK Steel Holding Corporation										(509.0)	(96.9)	(46.8)
Other comprehensive income (loss)										17.2	(527.8)	322.3
Comprehensive income (loss) attributable to AK Steel Holding Corporation										(491.8)	(624.7)	275.5
Current assets:
Cash and cash equivalents		0.0			0.0	0.0			0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
Accounts receivable, net													0.0	0.0
Inventory, net													0.0	0.0
Other current assets													0.0	0.3
Total current assets													0.0	0.3
Property, plant and equipment													0.0	0.0
Accumulated depreciation													0.0	0.0
Property, plant and equipment, net													0.0	0.0
Other non-current assets:
Investments in affiliates													0.0	0.0
Investment in subsidiaries													(3,541.0)	(2,970.9)
Inter-company accounts													2,563.4	2,478.1
Other non-current assets													0.0	0.0
TOTAL ASSETS													(977.6)	(492.5)
Current liabilities:
Accounts payable													0.0	0.0
Accrued liabilities													0.0	0.0
Current portion of pension and other postretirement benefit obligations													0.0	0.0
Total current liabilities													0.0	0.0
Non-current liabilities:
Long-term debt													0.0	0.0
Pension and other postretirement benefit obligations													0.0	0.0
Other non-current liabilities													0.0	0.0
TOTAL LIABILITIES													0.0	0.0
Equity (deficit):
Total stockholders' equity (deficit)													(977.6)	(492.5)
Noncontrolling interests													0.0	0.0
TOTAL EQUITY (DEFICIT)													(977.6)	(492.5)
TOTAL LIABILITIES AND EQUITY (DEFICIT)													(977.6)	(492.5)
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										(3.7)	(3.4)	(3.5)
Cash flows from investing activities:
Capital investments										0.0	0.0	0.0
Investments in Magnetation joint venture											0.0	0.0
Investments in acquired business, net of cash acquired											0.0
Proceeds from sale of equity investee										0.0
Proceeds from AFSG Holdings, Inc. distribution										0.0
Other investing items, net										0.0	0.0	0.0
Net cash flows from investing activities										0.0	0.0	0.0
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										0.0	0.0	0.0
Proceeds from issuance of long-term debt											0.0	0.0
Redemption of long-term debt										0.0	0.0	0.0
Proceeds from issuance of common stock											345.3
Debt issuance costs											0.0	0.0
Inter-company activity										4.7	(341.0)	4.1
SunCoke Middletown distributions to noncontrolling interest owners										0.0	0.0	0.0
Other financing items, net										(1.0)	(0.9)	(0.6)
Net cash flows from financing activities										3.7	3.4	3.5
Net increase (decrease) in cash and cash equivalents										0.0	0.0	0.0
Cash and cash equivalents, beginning of year					0.0				0.0	0.0	0.0	0.0
Cash and cash equivalents, end of year		0.0				0.0				0.0	0.0	0.0
AK Steel [Member]
Condensed Statements of Operations [Abstract]
Net sales										6,498.2	6,284.2	5,339.3
Cost of products sold (exclusive of items shown separately below)										5,984.9	5,937.6	5,012.1
Selling and administrative expenses (exclusive of items shown separately below)										270.4	251.0	205.0
Depreciation										187.7	176.1	169.4
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										(63.0)	(92.5)	(68.6)
Pension and OPEB net corridor charge										131.2	2.0
Charge for facility idling										28.1
Total operating costs										6,539.3	6,274.2	5,317.9
Operating profit (loss)										(41.1)	10.0	21.4
Interest expense										171.0	142.1	125.9
Impairment of Magnetation investment										0.0
Impairment of AFSG investment										0.0
Other income (expense)										6.4	(17.7)	(5.9)
Income (loss) before income taxes										(205.7)	(149.8)	(110.4)
Income tax expense (benefit)										39.6	(19.2)	(27.8)
Equity in net income (loss) of subsidiaries										(258.8)	38.3	40.2
Net income (loss)										(504.1)	(92.3)	(42.4)
Less: Net income attributable to noncontrolling interests										0.0	0.0	0.0
Net income (loss) attributable to AK Steel Holding Corporation										(504.1)	(92.3)	(42.4)
Other comprehensive income (loss)										17.2	(527.8)	322.3
Comprehensive income (loss) attributable to AK Steel Holding Corporation										(486.9)	(620.1)	279.9
Current assets:
Cash and cash equivalents		27.0			28.5	28.5			16.8	28.5	16.8	203.6	27.0	28.5	16.8	203.6
Accounts receivable, net													411.9	606.2
Inventory, net													1,149.6	1,080.5
Other current assets													75.6	67.9
Total current assets													1,664.1	1,783.1
Property, plant and equipment													5,763.8	5,695.8
Accumulated depreciation													(4,218.0)	(4,040.8)
Property, plant and equipment, net													1,545.8	1,655.0
Other non-current assets:
Investments in affiliates													42.6	84.5
Investment in subsidiaries													1,346.0	1,582.4
Inter-company accounts													(3,600.9)	(3,420.4)
Other non-current assets													83.0	174.4
TOTAL ASSETS													1,080.6	1,859.0
Current liabilities:
Accounts payable													669.0	754.9
Accrued liabilities													242.3	244.6
Current portion of pension and other postretirement benefit obligations													77.3	55.3
Total current liabilities													988.6	1,054.8
Non-current liabilities:
Long-term debt													2,354.1	2,422.0
Pension and other postretirement benefit obligations													1,143.6	1,221.3
Other non-current liabilities													135.3	131.8
TOTAL LIABILITIES													4,621.6	4,829.9
Equity (deficit):
Total stockholders' equity (deficit)													(3,541.0)	(2,970.9)
Noncontrolling interests													0.0	0.0
TOTAL EQUITY (DEFICIT)													(3,541.0)	(2,970.9)
TOTAL LIABILITIES AND EQUITY (DEFICIT)													1,080.6	1,859.0
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										49.0	(447.2)	(251.1)
Cash flows from investing activities:
Capital investments										(85.0)	(63.1)	(39.2)
Investments in Magnetation joint venture											0.0	0.0
Investments in acquired business, net of cash acquired											(690.3)
Proceeds from sale of equity investee										25.0
Proceeds from AFSG Holdings, Inc. distribution										0.0
Other investing items, net										12.5	13.6	8.5
Net cash flows from investing activities										(47.5)	(739.8)	(30.7)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										(55.0)	515.0	90.0
Proceeds from issuance of long-term debt											427.1	31.9
Redemption of long-term debt										(14.1)	(0.8)	(27.4)
Proceeds from issuance of common stock											0.0
Debt issuance costs											(15.5)	(3.4)
Inter-company activity										66.1	272.9	3.9
SunCoke Middletown distributions to noncontrolling interest owners										0.0	0.0	0.0
Other financing items, net										0.0	0.0	0.0
Net cash flows from financing activities										(3.0)	1,198.7	95.0
Net increase (decrease) in cash and cash equivalents										(1.5)	11.7	(186.8)
Cash and cash equivalents, beginning of year					28.5				16.8	28.5	16.8	203.6
Cash and cash equivalents, end of year		27.0				28.5				27.0	28.5	16.8
Guarantor Subsidiaries of the Senior Notes [Member]
Condensed Statements of Operations [Abstract]
Net sales										250.9	280.7	261.5
Cost of products sold (exclusive of items shown separately below)										167.5	199.3	189.0
Selling and administrative expenses (exclusive of items shown separately below)										10.7	11.3	10.5
Depreciation										3.6	3.9	4.3
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										0.0	0.0	0.0
Pension and OPEB net corridor charge										0.0	0.0
Charge for facility idling										0.0
Total operating costs										181.8	214.5	203.8
Operating profit (loss)										69.1	66.2	57.7
Interest expense										0.0	0.0	0.0
Impairment of Magnetation investment										0.0
Impairment of AFSG investment										0.0
Other income (expense)										6.6	6.5	6.1
Income (loss) before income taxes										75.7	72.7	63.8
Income tax expense (benefit)										28.7	29.1	20.1
Equity in net income (loss) of subsidiaries										0.0	0.0	0.0
Net income (loss)										47.0	43.6	43.7
Less: Net income attributable to noncontrolling interests										0.0	0.0	0.0
Net income (loss) attributable to AK Steel Holding Corporation										47.0	43.6	43.7
Other comprehensive income (loss)										0.0	0.0	0.0
Comprehensive income (loss) attributable to AK Steel Holding Corporation										47.0	43.6	43.7
Current assets:
Cash and cash equivalents		0.0			0.5	0.5			0.0	0.5	0.0	0.0	0.0	0.5	0.0	0.0
Accounts receivable, net													23.5	27.6
Inventory, net													26.1	26.2
Other current assets													0.3	0.2
Total current assets													49.9	54.5
Property, plant and equipment													103.1	97.3
Accumulated depreciation													(75.4)	(71.8)
Property, plant and equipment, net													27.7	25.5
Other non-current assets:
Investments in affiliates													0.0	0.0
Investment in subsidiaries													0.0	0.0
Inter-company accounts													1,403.0	1,325.5
Other non-current assets													33.0	33.0
TOTAL ASSETS													1,513.6	1,438.5
Current liabilities:
Accounts payable													6.3	6.9
Accrued liabilities													2.8	3.0
Current portion of pension and other postretirement benefit obligations													0.0	0.0
Total current liabilities													9.1	9.9
Non-current liabilities:
Long-term debt													0.0	0.0
Pension and other postretirement benefit obligations													0.0	0.0
Other non-current liabilities													0.0	0.0
TOTAL LIABILITIES													9.1	9.9
Equity (deficit):
Total stockholders' equity (deficit)													1,504.5	1,428.6
Noncontrolling interests													0.0	0.0
TOTAL EQUITY (DEFICIT)													1,504.5	1,428.6
TOTAL LIABILITIES AND EQUITY (DEFICIT)													1,513.6	1,438.5
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										53.9	39.2	50.4
Cash flows from investing activities:
Capital investments										(5.8)	(2.8)	(1.7)
Investments in Magnetation joint venture											0.0	0.0
Investments in acquired business, net of cash acquired											0.0
Proceeds from sale of equity investee										0.0
Proceeds from AFSG Holdings, Inc. distribution										0.0
Other investing items, net										0.0	0.0	0.3
Net cash flows from investing activities										(5.8)	(2.8)	(1.4)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										0.0	0.0	0.0
Proceeds from issuance of long-term debt											0.0	0.0
Redemption of long-term debt										0.0	0.0	0.0
Proceeds from issuance of common stock											0.0
Debt issuance costs											0.0	0.0
Inter-company activity										(48.6)	(35.9)	(49.0)
SunCoke Middletown distributions to noncontrolling interest owners										0.0	0.0	0.0
Other financing items, net										0.0	0.0	0.0
Net cash flows from financing activities										(48.6)	(35.9)	(49.0)
Net increase (decrease) in cash and cash equivalents										(0.5)	0.5	0.0
Cash and cash equivalents, beginning of year					0.5				0.0	0.5	0.0	0.0
Cash and cash equivalents, end of year		0.0				0.5				0.0	0.5	0.0
Other Non-Guarantor Subsidiaries [Member]
Condensed Statements of Operations [Abstract]
Net sales										538.3	599.6	568.8
Cost of products sold (exclusive of items shown separately below)										423.3	484.7	463.3
Selling and administrative expenses (exclusive of items shown separately below)										25.0	28.3	26.2
Depreciation										24.7	21.9	16.4
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										0.0	0.0	0.0
Pension and OPEB net corridor charge										0.0	0.0
Charge for facility idling										0.0
Total operating costs										473.0	534.9	505.9
Operating profit (loss)										65.3	64.7	62.9
Interest expense										2.0	2.6	1.5
Impairment of Magnetation investment										(256.3)
Impairment of AFSG investment										(41.6)
Other income (expense)										(11.6)	(9.9)	(1.6)
Income (loss) before income taxes										(246.2)	52.2	59.8
Income tax expense (benefit)										(4.2)	(3.4)	(2.0)
Equity in net income (loss) of subsidiaries										0.0	0.0	0.0
Net income (loss)										(242.0)	55.6	61.8
Less: Net income attributable to noncontrolling interests										62.8	62.8	64.2
Net income (loss) attributable to AK Steel Holding Corporation										(304.8)	(7.2)	(2.4)
Other comprehensive income (loss)										(3.1)	(3.7)	1.2
Comprehensive income (loss) attributable to AK Steel Holding Corporation										(307.9)	(10.9)	(1.2)
Current assets:
Cash and cash equivalents		29.6			41.2	41.2			28.5	41.2	28.5	23.4	29.6	41.2	28.5	23.4
Accounts receivable, net													32.0	37.3
Inventory, net													60.6	73.5
Other current assets													2.5	3.0
Total current assets													124.7	155.0
Property, plant and equipment													599.1	595.3
Accumulated depreciation													(86.1)	(62.6)
Property, plant and equipment, net													513.0	532.7
Other non-current assets:
Investments in affiliates													28.1	304.2
Investment in subsidiaries													0.0	0.0
Inter-company accounts													(390.8)	(412.4)
Other non-current assets													5.0	60.7
TOTAL ASSETS													280.0	640.2
Current liabilities:
Accounts payable													29.1	42.0
Accrued liabilities													16.4	18.9
Current portion of pension and other postretirement benefit obligations													0.4	0.3
Total current liabilities													45.9	61.2
Non-current liabilities:
Long-term debt													0.0	0.0
Pension and other postretirement benefit obligations													3.3	4.0
Other non-current liabilities													1.1	0.7
TOTAL LIABILITIES													50.3	65.9
Equity (deficit):
Total stockholders' equity (deficit)													(152.3)	158.8
Noncontrolling interests													382.0	415.5
TOTAL EQUITY (DEFICIT)													229.7	574.3
TOTAL LIABILITIES AND EQUITY (DEFICIT)													280.0	640.2
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										104.8	91.3	129.6
Cash flows from investing activities:
Capital investments										(8.2)	(15.2)	(22.7)
Investments in Magnetation joint venture											(100.0)	(50.0)
Investments in acquired business, net of cash acquired											0.0
Proceeds from sale of equity investee										0.0
Proceeds from AFSG Holdings, Inc. distribution										14.0
Other investing items, net										0.0	0.0	6.3
Net cash flows from investing activities										5.8	(115.2)	(66.4)
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										0.0	0.0	0.0
Proceeds from issuance of long-term debt											0.0	0.0
Redemption of long-term debt										0.0	0.0	0.0
Proceeds from issuance of common stock											0.0
Debt issuance costs											0.0	0.0
Inter-company activity										(25.9)	101.3	5.4
SunCoke Middletown distributions to noncontrolling interest owners										(96.3)	(61.0)	(64.8)
Other financing items, net										0.0	(3.7)	1.3
Net cash flows from financing activities										(122.2)	36.6	(58.1)
Net increase (decrease) in cash and cash equivalents										(11.6)	12.7	5.1
Cash and cash equivalents, beginning of year					41.2				28.5	41.2	28.5	23.4
Cash and cash equivalents, end of year		29.6				41.2				29.6	41.2	28.5
Eliminations [Member]
Condensed Statements of Operations [Abstract]
Net sales										(594.5)	(658.8)	(599.2)
Cost of products sold (exclusive of items shown separately below)										(543.7)	(613.9)	(556.6)
Selling and administrative expenses (exclusive of items shown separately below)										(49.1)	(48.0)	(40.8)
Depreciation										0.0	0.0	0.0
Pension and OPEB expense (income) (exclusive of corridor charges shown below)										0.0	0.0	0.0
Pension and OPEB net corridor charge										0.0	0.0
Charge for facility idling										0.0
Total operating costs										(592.8)	(661.9)	(597.4)
Operating profit (loss)										(1.7)	3.1	(1.8)
Interest expense										0.0	0.0	0.0
Impairment of Magnetation investment										0.0
Impairment of AFSG investment										0.0
Other income (expense)										0.0	0.0	0.0
Income (loss) before income taxes										(1.7)	3.1	(1.8)
Income tax expense (benefit)										(0.7)	1.2	(0.7)
Equity in net income (loss) of subsidiaries										762.9	54.0	2.2
Net income (loss)										761.9	55.9	1.1
Less: Net income attributable to noncontrolling interests										0.0	0.0	0.0
Net income (loss) attributable to AK Steel Holding Corporation										761.9	55.9	1.1
Other comprehensive income (loss)										(14.1)	531.5	(323.5)
Comprehensive income (loss) attributable to AK Steel Holding Corporation										747.8	587.4	(322.4)
Current assets:
Cash and cash equivalents		0.0			0.0	0.0			0.0	0.0	0.0	0.0	0.0	0.0	$ 0.0	$ 0.0
Accounts receivable, net													(22.5)	(26.8)
Inventory, net													(10.0)	(8.1)
Other current assets													0.0	0.0
Total current assets													(32.5)	(34.9)
Property, plant and equipment													0.0	0.0
Accumulated depreciation													0.0	0.0
Property, plant and equipment, net													0.0	0.0
Other non-current assets:
Investments in affiliates													0.0	0.0
Investment in subsidiaries													2,195.0	1,388.5
Inter-company accounts													25.3	29.2
Other non-current assets													0.0	0.0
TOTAL ASSETS													2,187.8	1,382.8
Current liabilities:
Accounts payable													(1.0)	(0.7)
Accrued liabilities													0.0	0.0
Current portion of pension and other postretirement benefit obligations													0.0	0.0
Total current liabilities													(1.0)	(0.7)
Non-current liabilities:
Long-term debt													0.0	0.0
Pension and other postretirement benefit obligations													0.0	0.0
Other non-current liabilities													0.0	0.0
TOTAL LIABILITIES													(1.0)	(0.7)
Equity (deficit):
Total stockholders' equity (deficit)													2,188.8	1,383.5
Noncontrolling interests													0.0	0.0
TOTAL EQUITY (DEFICIT)													2,188.8	1,383.5
TOTAL LIABILITIES AND EQUITY (DEFICIT)													$ 2,187.8	$ 1,382.8
Condensed Cash Flows [Abstract]
Net cash flows from operating activities										(3.7)	(2.7)	(35.6)
Cash flows from investing activities:
Capital investments										0.0	0.0	0.0
Investments in Magnetation joint venture											0.0	0.0
Investments in acquired business, net of cash acquired											0.0
Proceeds from sale of equity investee										0.0
Proceeds from AFSG Holdings, Inc. distribution										0.0
Other investing items, net										0.0	0.0	0.0
Net cash flows from investing activities										0.0	0.0	0.0
Cash flows from financing activities:
Net borrowings (repayments) under credit facility										0.0	0.0	0.0
Proceeds from issuance of long-term debt											0.0	0.0
Redemption of long-term debt										0.0	0.0	0.0
Proceeds from issuance of common stock											0.0
Debt issuance costs											0.0	0.0
Inter-company activity										3.7	2.7	35.6
SunCoke Middletown distributions to noncontrolling interest owners										0.0	0.0	0.0
Other financing items, net										0.0	0.0	0.0
Net cash flows from financing activities										3.7	2.7	35.6
Net increase (decrease) in cash and cash equivalents										0.0	0.0	0.0
Cash and cash equivalents, beginning of year					$ 0.0				$ 0.0	0.0	0.0	0.0
Cash and cash equivalents, end of year		$ 0.0				$ 0.0				$ 0.0	$ 0.0	$ 0.0
Senior Secured Notes Due December 2018 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)													8.75%	8.75%
Senior Notes Due May 2020 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)													7.625%	7.625%
Senior Notes Due October 2021 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)	7.625%												7.625%	7.625%
Senior Notes Due April 2022 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)													8.375%	8.375%
Exchangeable Senior Notes Due November 2019 [Member]
Condensed Financial Statements, Captions [Line Items]
Debt Instrument, Interest Rate, Stated Percentage (in hundredths)													5.00%	5.00%