Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 14.4	$ (16.5)	$ 28.0	$ (22.6)
Other comprehensive income (loss):
Reclassifications of prior service benefit, actuarial loss amortization and curtailment gain to earnings (net of related tax benefit of $0.1 and $3.9 million for the three and nine months ended September 30, 2015, respectively)	0.0	(0.1)	0.0	5.7
Currency translation adjustment	(0.1)	(1.6)	1.0	(3.2)
Comprehensive income (loss)	14.3	(18.2)	29.0	(20.1)
Less: Comprehensive income attributable to noncontrolling interests	8.3	7.0	30.6	18.4
Comprehensive income (loss) attributable to SunCoke Energy, Inc.	$ 6.0	$ (25.2)	$ (1.6)	$ (38.5)