Guarantor Non-Guarantor Subsidiary Financial Information (Details) - Consolidating Balance Sheets - USD ($) $ in Millions	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents (including restricted cash of $0 and $16, respectively)	$ 130		$ 115	$ 128	$ 196
Accounts receivable, net	473		462
Intercompany accounts receivable	0		0
Intercompany loans receivable - current portion	0		0
Finished and in-process goods	245		221
Raw materials and supplies	103		92
Current assets held for sale	0		6
Other current assets	62	$ 56	44
Total current assets	1,013		940
Investment in unconsolidated entities	22		20
Deferred income taxes	9		8
Long-term assets held for sale	0		2
Other assets, net	42		49
Intercompany loans receivable	0		0
Property and equipment, net	858		924
Goodwill	110		112
Other intangible assets, net	32		42
Total assets	2,086		2,097
Current liabilities
Accounts payable	397		402
Intercompany accounts payable	0		0
Debt payable within one year	82		125
Intercompany loans payable within one year	0		0
Interest payable	82		82
Income taxes payable	10		12
Accrued payroll and incentive compensation	60		47
Current liabilities associated with assets held for sale	0		2
Other current liabilities	119		135
Total current liabilities	750		805
Long-term liabilities
Long-term debt	3,678		3,584
Intercompany loans payable	0		0
Accumulated losses of unconsolidated subsidiaries in excess of investment	0		0
Long-term pension and post employment benefit obligations	246		262
Deferred income taxes	11		11
Other long-term liabilities	178		177
Total liabilities	4,863		4,839
Total Hexion Inc. shareholder’s deficit	(2,777)		(2,741)
Noncontrolling interest	0		(1)
Total deficit	(2,777)		(2,742)
Total liabilities and deficit	2,086		2,097
Hexion Inc. [Member]
Current assets
Cash and cash equivalents (including restricted cash of $0 and $16, respectively)	42		13	11	28
Accounts receivable, net	116		126
Intercompany accounts receivable	58		121
Intercompany loans receivable - current portion	123		1
Finished and in-process goods	97		85
Raw materials and supplies	39		36
Current assets held for sale			1
Other current assets	23		19
Total current assets	498		402
Investment in unconsolidated entities	144		158
Deferred income taxes	0		0
Long-term assets held for sale			0
Other assets, net	13		17
Intercompany loans receivable	1,098		1,114
Property and equipment, net	374		410
Goodwill	52		52
Other intangible assets, net	23		32
Total assets	2,202		2,185
Current liabilities
Accounts payable	130		129
Intercompany accounts payable	56		80
Debt payable within one year	8		10
Intercompany loans payable within one year	0		22
Interest payable	81		80
Income taxes payable	5		6
Accrued payroll and incentive compensation	31		22
Current liabilities associated with assets held for sale			0
Other current liabilities	69		70
Total current liabilities	380		419
Long-term liabilities
Long-term debt	3,520		3,507
Intercompany loans payable	135		190
Accumulated losses of unconsolidated subsidiaries in excess of investment	804		668
Long-term pension and post employment benefit obligations	29		31
Deferred income taxes	1		2
Other long-term liabilities	110		109
Total liabilities	4,979		4,926
Total Hexion Inc. shareholder’s deficit			(2,741)
Noncontrolling interest			0
Total deficit	(2,777)		(2,741)
Total liabilities and deficit	2,202		2,185
Combined Subsidiary Guarantors [Member]
Current assets
Cash and cash equivalents (including restricted cash of $0 and $16, respectively)	0		0	0	0
Accounts receivable, net	1		1
Intercompany accounts receivable	0		0
Intercompany loans receivable - current portion	0		0
Finished and in-process goods	0		0
Raw materials and supplies	0		0
Current assets held for sale			0
Other current assets	0		0
Total current assets	1		1
Investment in unconsolidated entities	14		13
Deferred income taxes	0		0
Long-term assets held for sale			0
Other assets, net	7		8
Intercompany loans receivable	0		0
Property and equipment, net	0		0
Goodwill	0		0
Other intangible assets, net	0		0
Total assets	22		22
Current liabilities
Accounts payable	0		0
Intercompany accounts payable	0		0
Debt payable within one year	0		0
Intercompany loans payable within one year	0		0
Interest payable	0		0
Income taxes payable	0		0
Accrued payroll and incentive compensation	0		0
Current liabilities associated with assets held for sale			0
Other current liabilities	0		0
Total current liabilities	0		0
Long-term liabilities
Long-term debt	0		0
Intercompany loans payable	0		0
Accumulated losses of unconsolidated subsidiaries in excess of investment	157		171
Long-term pension and post employment benefit obligations	0		0
Deferred income taxes	0		0
Other long-term liabilities	0		0
Total liabilities	157		171
Total Hexion Inc. shareholder’s deficit			(149)
Noncontrolling interest			0
Total deficit	(135)		(149)
Total liabilities and deficit	22		22
Combined Non-Guarantor Subsidiaries [Member]
Current assets
Cash and cash equivalents (including restricted cash of $0 and $16, respectively)	88		102	117	168
Accounts receivable, net	356		335
Intercompany accounts receivable	56		80
Intercompany loans receivable - current portion	0		22
Finished and in-process goods	148		136
Raw materials and supplies	64		56
Current assets held for sale			5
Other current assets	39		25
Total current assets	751		761
Investment in unconsolidated entities	21		20
Deferred income taxes	9		8
Long-term assets held for sale			2
Other assets, net	22		24
Intercompany loans receivable	135		190
Property and equipment, net	484		514
Goodwill	58		60
Other intangible assets, net	9		10
Total assets	1,489		1,589
Current liabilities
Accounts payable	267		273
Intercompany accounts payable	58		121
Debt payable within one year	74		115
Intercompany loans payable within one year	123		1
Interest payable	1		2
Income taxes payable	5		6
Accrued payroll and incentive compensation	29		25
Current liabilities associated with assets held for sale			2
Other current liabilities	50		65
Total current liabilities	607		610
Long-term liabilities
Long-term debt	158		77
Intercompany loans payable	1,098		1,114
Accumulated losses of unconsolidated subsidiaries in excess of investment	0		0
Long-term pension and post employment benefit obligations	217		231
Deferred income taxes	10		9
Other long-term liabilities	68		68
Total liabilities	2,158		2,109
Total Hexion Inc. shareholder’s deficit			(519)
Noncontrolling interest			(1)
Total deficit	(669)		(520)
Total liabilities and deficit	1,489		1,589
Consolidation, Eliminations [Member]
Current assets
Cash and cash equivalents (including restricted cash of $0 and $16, respectively)	0		0	$ 0	$ 0
Accounts receivable, net	0		0
Intercompany accounts receivable	(114)		(201)
Intercompany loans receivable - current portion	(123)		(23)
Finished and in-process goods	0		0
Raw materials and supplies	0		0
Current assets held for sale			0
Other current assets	0		0
Total current assets	(237)		(224)
Investment in unconsolidated entities	(157)		(171)
Deferred income taxes	0		0
Long-term assets held for sale			0
Other assets, net	0		0
Intercompany loans receivable	(1,233)		(1,304)
Property and equipment, net	0		0
Goodwill	0		0
Other intangible assets, net	0		0
Total assets	(1,627)		(1,699)
Current liabilities
Accounts payable	0		0
Intercompany accounts payable	(114)		(201)
Debt payable within one year	0		0
Intercompany loans payable within one year	(123)		(23)
Interest payable	0		0
Income taxes payable	0		0
Accrued payroll and incentive compensation	0		0
Current liabilities associated with assets held for sale			0
Other current liabilities	0		0
Total current liabilities	(237)		(224)
Long-term liabilities
Long-term debt	0		0
Intercompany loans payable	(1,233)		(1,304)
Accumulated losses of unconsolidated subsidiaries in excess of investment	(961)		(839)
Long-term pension and post employment benefit obligations	0		0
Deferred income taxes	0		0
Other long-term liabilities	0		0
Total liabilities	(2,431)		(2,367)
Total Hexion Inc. shareholder’s deficit			668
Noncontrolling interest			0
Total deficit	804		668
Total liabilities and deficit	$ (1,627)		$ (1,699)