Guarantor Non-Guarantor Subsidiary Financial Information (Details) - Consolidating Statement of Operations - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Net sales	$ 952	$ 914	$ 2,893	$ 2,696
Cost of sales	796	797	2,414	2,312
Gross profit	156	117	479	384
Selling, general and administrative expense	72	77	231	233
Gain on disposition	0	0	(44)	0
Asset impairments	3	13	28	13
Business realignment costs	(5)	(10)	(19)	(27)
Other operating expense, net	6	1	26	4
Operating income	70	16	219	107
Interest expense, net	83	82	250	247
Intercompany interest (income) expense, net	0	0	0	0
Loss on extinguishment of debt	0	0	0	3
Other non-operating (income) expense, net	(1)	(5)	6	(10)
(Loss) income before tax and earnings from unconsolidated entities	12	61	37	133
Income tax expense	6	9	17	16
Loss before earnings from unconsolidated entities	(18)	(70)	(54)	(149)
Earnings from unconsolidated entities, net of taxes	0	0	2	3
Net loss	(18)	(70)	(52)	(146)
Net income attributable to noncontrolling interest	0	0	(1)	0
Net (loss) income attributable to Hexion Inc.	(18)	(70)	(53)	(146)
Comprehensive (loss) income attributable to Hexion Inc.	(24)	(60)	(61)	(121)
Hexion Inc. [Member]
Net sales	438	400	1,329	1,195
Cost of sales	361	360	1,088	1,037
Gross profit	77	40	241	158
Selling, general and administrative expense	28	29	108	96
Gain on disposition			(24)
Asset impairments	0	13	25	13
Business realignment costs	(3)	(6)	(12)	(16)
Other operating expense, net	2	3	5	0
Operating income	44	(11)	115	33
Interest expense, net	80	78	239	236
Intercompany interest (income) expense, net	(21)	(20)	(62)	(55)
Loss on extinguishment of debt				3
Other non-operating (income) expense, net	0	(25)	17	(83)
(Loss) income before tax and earnings from unconsolidated entities	15	44	79	68
Income tax expense	0	3	(6)	(1)
Loss before earnings from unconsolidated entities	(15)	(47)	(73)	(67)
Earnings from unconsolidated entities, net of taxes	(3)	(23)	20	(79)
Net loss	(18)		(53)
Net income attributable to noncontrolling interest			0
Net (loss) income attributable to Hexion Inc.		(70)	(53)	(146)
Comprehensive (loss) income attributable to Hexion Inc.	(24)	(60)	(61)	(121)
Combined Subsidiary Guarantors [Member]
Net sales	0	0	0	0
Cost of sales	0	0	0	0
Gross profit	0	0	0	0
Selling, general and administrative expense	0	0	0	0
Gain on disposition			0
Asset impairments	0	0	0	0
Business realignment costs	0	0	0	0
Other operating expense, net	0	0	0	0
Operating income	0	0	0	0
Interest expense, net	0	0	0	0
Intercompany interest (income) expense, net	0	0	0	0
Loss on extinguishment of debt				0
Other non-operating (income) expense, net	0	0	0	0
(Loss) income before tax and earnings from unconsolidated entities	0	0	0	0
Income tax expense	0	0	0	0
Loss before earnings from unconsolidated entities	0	0	0	0
Earnings from unconsolidated entities, net of taxes	0	(18)	14	(52)
Net loss	0		14
Net income attributable to noncontrolling interest			0
Net (loss) income attributable to Hexion Inc.		(18)	14	(52)
Comprehensive (loss) income attributable to Hexion Inc.	0	(18)	14	(52)
Combined Non-Guarantor Subsidiaries [Member]
Net sales	562	558	1,715	1,651
Cost of sales	483	481	1,477	1,425
Gross profit	79	77	238	226
Selling, general and administrative expense	44	48	123	137
Gain on disposition			(20)
Asset impairments	3	0	3	0
Business realignment costs	(2)	(4)	(7)	(11)
Other operating expense, net	4	(2)	21	4
Operating income	26	27	104	74
Interest expense, net	3	4	11	11
Intercompany interest (income) expense, net	21	20	62	55
Loss on extinguishment of debt				0
Other non-operating (income) expense, net	(1)	20	(11)	73
(Loss) income before tax and earnings from unconsolidated entities	(3)	17	(42)	65
Income tax expense	6	6	23	17
Loss before earnings from unconsolidated entities	(3)	(23)	19	(82)
Earnings from unconsolidated entities, net of taxes	1	1	3	3
Net loss	(2)		22
Net income attributable to noncontrolling interest			(1)
Net (loss) income attributable to Hexion Inc.		(22)	21	(79)
Comprehensive (loss) income attributable to Hexion Inc.	(11)	(22)	26	(71)
Consolidation, Eliminations [Member]
Net sales	(48)	(44)	(151)	(150)
Cost of sales	(48)	(44)	(151)	(150)
Gross profit	0	0	0	0
Selling, general and administrative expense	0	0	0	0
Gain on disposition			0
Asset impairments	0	0	0	0
Business realignment costs	0	0	0	0
Other operating expense, net	0	0	0	0
Operating income	0	0	0	0
Interest expense, net	0	0	0	0
Intercompany interest (income) expense, net	0	0	0	0
Loss on extinguishment of debt				0
Other non-operating (income) expense, net	0	0	0	0
(Loss) income before tax and earnings from unconsolidated entities	0	0	0	0
Income tax expense	0	0	0	0
Loss before earnings from unconsolidated entities	0	0	0	0
Earnings from unconsolidated entities, net of taxes	2	40	(35)	131
Net loss	2		(35)
Net income attributable to noncontrolling interest			0
Net (loss) income attributable to Hexion Inc.		40	(35)	131
Comprehensive (loss) income attributable to Hexion Inc.	$ 11	$ 40	$ (40)	$ 123