Consolidated Statements of Comprehensive Loss - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 12.6	$ 0.4
Other comprehensive income (loss):
Reclassifications of prior service benefit, actuarial loss amortization and curtailment gain to earnings (net of related tax expense of $1.6 million for the three months ended March 31, 2015)	0.0	(2.4)
Currency translation adjustment	0.4	(1.1)
Comprehensive income (loss)	13.0	(3.1)
Less: Comprehensive income attributable to noncontrolling interests	16.7	4.4
Comprehensive loss attributable to SunCoke Energy, Inc.	$ (3.7)	$ (7.5)