星空传媒 Inc. Annual report pursuant to Section 13 and 15(d)

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Narrative) (Details)

DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]	听	听	听
Natural Gas Hedges	$ 3.5	听	听
Unrealized net gain (loss) on derivative financial instruments, net of tax	$ 0.5	$ 2.6	$ (20.7)
Current Fiscal Year End Date	--12-31	听	听
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$ 104.7	92.6	5.5
Derivative asset, fair value	39.4	33.1	听
Derivative liability, fair value	2.7	0.5	听
Derivative assets	39.4	33.1	听
Accounts receivable, net	140.6	128.7	听
Not Designated as Hedging Instrument [Member]	听	听	听
Derivative [Line Items]	听	听	听
Derivative asset, fair value	39.4	33.1	听
Derivative liability, fair value	2.4	0.5	听
Foreign Exchange Contract [Member] \| Other Nonoperating Income (Expense) [Member]	听	听	听
Derivative [Line Items]	听	听	听
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	听	听	(3.6)
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0.0	0.0	听
Foreign Exchange Contract [Member] \| Product Revenues [Member]	听	听	听
Derivative [Line Items]	听	听	听
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0.0	0.0	(12.6)
Customer Supply Agreement [Member] \| Not Designated as Hedging Instrument [Member] \| Product Revenues [Member]	听	听	听
Derivative [Line Items]	听	听	听
Derivative, Gain (Loss) on Derivative, Net	163.3	41.7	27.1
Provisional Pricing Arrangements [Member] \| Product Revenues [Member]	听	听	听
Derivative [Line Items]	听	听	听
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	(58.6)	49.0	(1.4)
Provisional Pricing Arrangements [Member] \| Not Designated as Hedging Instrument [Member] \| U S Iron Ore And Asia Pacific Iron Ore [Member] \| Product Revenues [Member]	听	听	听
Derivative [Line Items]	听	听	听
Derivative, Gain (Loss) on Derivative, Net	58.6	49.0	$ (1.4)
Market Approach Valuation Technique [Member] \| Fair Value, Inputs, Level 3 [Member] \| Customer Supply Agreement [Member] \| Not Designated as Hedging Instrument [Member] \| Other Current Assets [Member]	听	听	听
Derivative [Line Items]	听	听	听
Derivative asset, fair value	37.9	21.3	听
Market Approach Valuation Technique [Member] \| Fair Value, Inputs, Level 3 [Member] \| Provisional Pricing Arrangements [Member] \| Not Designated as Hedging Instrument [Member] \| Other Current Assets [Member]	听	听	听
Derivative [Line Items]	听	听	听
Derivative asset, fair value	1.5	10.3	听
Market Approach Valuation Technique [Member] \| Fair Value, Inputs, Level 3 [Member] \| Provisional Pricing Arrangements [Member] \| Not Designated as Hedging Instrument [Member] \| Other Current Liabilities [Member]	听	听	听
Derivative [Line Items]	听	听	听
Derivative liability, fair value	$ 2.4	$ 0.5	听