Consolidated Statement of Equity (Deficit) - USD ($) $ in Millions	Total	Common Stock [Member]	Paid-in Capital [Member]	Treasury Stock [Member]	Notes Receivable From Parent [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]	Total Hexion Inc. Deficit [Member]	Noncontrolling Interest [Member]
Balance at Dec. 31, 2017	$ (2,742)	$ 1	$ (526)	$ 296	$ 0	$ (8)	$ (2,964)	$ (2,741)	$ (1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(162)	0	0	0	0	0	(162)	(162)
Net (loss) income	(163)
Add: Net income (loss) attributable to noncontrolling interest	(1)								(1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		0	0	0	0		0	(10)
Other comprehensive loss	(10)					(10)			0
Cumulative Effect of New Accounting Principle in Period of Adoption	1	0	0	0	0	0	1	1	0
Return of capital to parent (see Note 9)	0
Balance at Dec. 31, 2018	(2,914)	1	(526)	296	0	(18)	(3,125)	(2,912)	(2)
Balance at Jul. 01, 2019	(1)	0	0	0	0	0	0	0	(1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(89)
Net (loss) income	(88)	0	0	0	0	0	(89)	(89)	1
Add: Net income (loss) attributable to noncontrolling interest	1
Other comprehensive loss	(1)	0	0	0	0	(1)	0	(1)	0
Stock-based compensation	8	0		0	0	0	0	8	0
Return of capital to parent (see Note 9)	0
Balance at Dec. 31, 2019	1,075	0	1,165	0	0	(1)	(89)	1,075	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(230)
Net (loss) income	(230)	0	0	0	0	0	(230)	(230)	0
Add: Net income (loss) attributable to noncontrolling interest	0
Other comprehensive loss	(26)	0	0	0	0	(26)	0	(26)	0
Stock-based compensation	17	0		0	0	0	0	17	0
Return of capital to parent (see Note 9)	(13)	0	(13)	0	0	0	0	(13)	0
Disbursement of Affiliated Loan	(10)	0	0	0	(10)	0	0	(10)	0
Settlement of affiliate loan	10	0	0	0	10	0	0	10	0
Balance at Dec. 31, 2020	$ 823	$ 0	$ 1,169	$ 0	$ 0	$ (27)	$ (319)	$ 823	$ 0