Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2019	Jun. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Other comprehensive (loss) income, net of tax:
Net (loss) income	$ (88)	$ 2,895	$ (163)	$ (234)
Foreign currency translation adjustments	(3)	(8)	(8)	33
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax	2	0	0	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax	0	0	(2)	(2)
Other comprehensive (loss) income	1	8	10	(31)
Comprehensive (loss) income	(89)	2,887	(173)	(203)
Comprehensive (income) loss attributable to noncontrolling interest	1	1	(1)	0
Comprehensive (loss) income attributable to Hexion Inc.	(90)	2,886	(172)	(203)
Parent [Member]
Other comprehensive (loss) income, net of tax:
Net (loss) income	(89)		(162)
Other comprehensive (loss) income	1	8	10	(31)
Noncontrolling Interest [Member]
Other comprehensive (loss) income, net of tax:
Net (loss) income	1		(1)
Other comprehensive (loss) income	$ 0	$ 0	$ 0	$ 0