CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities:
Net income	$ 88.0	$ 117.1
Depreciation	100.0	109.8
Amortization	17.5	17.3
Ashland Works closure	64.1	0.0
Deferred income taxes	0.6	(7.2)
Pension and OPEB expense (income)	2.5	(16.2)
Contributions to pension trust	(19.5)	(15.2)
Other postretirement benefit payments	(15.6)	(19.3)
Mark-to-market (gains) losses on derivative contracts	(61.1)	(7.4)
Changes in working capital	(33.4)	28.8
Other operating items, net	(6.9)	(20.3)
Net cash flows from operating activities	136.2	187.4
Cash flows from investing activities:
Capital investments	(82.4)	(64.0)
Other investing items, net	10.3	0.3
Net cash flows from investing activities	(72.1)	(63.7)
Cash flows from financing activities:
Net borrowings (payments) under credit facility	(50.0)	(80.0)
Redemption of long-term debt	(4.2)	0.0
SunCoke Middletown distributions to noncontrolling interest owners	(15.3)	(34.8)
Other financing items, net	(1.0)	(0.9)
Net cash flows from financing activities	(70.5)	(115.7)
Net increase (decrease) in cash and cash equivalents	(6.4)	8.0
Cash and cash equivalents, beginning of period	48.6	38.0
Cash and cash equivalents, end of period	42.2	46.0
Consolidated Entity Excluding Variable Interest Entities (VIE) [Member]
Cash flows from operating activities:
Depreciation	86.4	102.1
Variable Interest Entity, Primary Beneficiary [Member] | SunCoke Middletown [Member]
Cash flows from operating activities:
Depreciation	13.6	7.7
Net cash flows from operating activities	17.9	37.5
Cash flows from financing activities:
SunCoke Middletown distributions to noncontrolling interest owners	$ (15.3)	$ (34.8)