VARIABLE INTEREST ENTITIES (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
Net Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest	$ 41.0	$ 0.0	$ 0.0
Cash and cash equivalents	112.0	353.0
Inventories	3,828.0	317.0
Property, plant and equipment, net	8,743.0	1,929.0	$ 1,286.0
Accounts Payable, Current	(1,575.0)	(193.0)
Stockholders' Equity Attributable to Noncontrolling Interest	(323.0)	$ 0.0
Variable Interest Entity, Primary Beneficiary [Member] | SunCoke Middletown [Member]
Variable Interest Entity [Line Items]
Net Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest	41.0
Cash and cash equivalents	5.0
Inventories	21.0
Property, plant and equipment, net	308.0
Accounts Payable, Current	(15.0)
Other Assets (Liabilities), Net	(10.0)
Stockholders' Equity Attributable to Noncontrolling Interest	$ (309.0)