Guarantor Non-Guarantor Subsidiary Financial Information Level 4 (Details) - Consolidating Balance Sheets - USD ($) $ in Millions	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Current assets
Cash and cash equivalents (including restricted cash of $0 and $18, respectively)	$ 113		$ 115	$ 123	$ 196
Accounts receivable, net	504		462
Intercompany accounts receivable	0		0
Intercompany loans receivable - current portion	0		0
Finished and in-process goods	255		221
Raw materials and supplies	95		92
Current assets held for sale	0		6
Other current assets	56	$ 56	44
Total current assets	1,023		940
Investment in unconsolidated entities	21		20
Deferred income taxes	8		8
Long-term assets held for sale	0		2
Other Assets, Noncurrent	46		49
Intercompany loans receivable	0		0
Property, Plant and Equipment, Net	900		924
Goodwill	113		112
Other intangible assets, net	34		42
Total assets	2,145		2,097
Current liabilities
Accounts and drafts payable	372		402
Intercompany accounts payable	0		0
Debt payable within one year	66		125
Intercompany loans payable within one year	0		0
Interest payable	101		82
Income taxes payable	12		12
Accrued payroll and incentive compensation	63		47
Current liabilities associated with assets held for sale	0		2
Other current liabilities	121		135
Total current liabilities	735		805
Long-term liabilities
Long-term debt	3,703		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	256		262
Deferred income taxes	11		11
Other long-term liabilities	180		177
Total liabilities	4,885		4,839
Total Hexion Inc. shareholder’s deficit	(2,739)		(2,741)
Noncontrolling interest	(1)		(1)
Total deficit	(2,740)		(2,742)
Total liabilities and deficit	2,145		2,097
Hexion Inc. [Member]
Current assets
Cash and cash equivalents (including restricted cash of $0 and $18, respectively)	19		13	12	28
Accounts receivable, net	128		126
Intercompany accounts receivable	136		121
Intercompany loans receivable - current portion	8		1
Finished and in-process goods	92		85
Raw materials and supplies	35		36
Current assets held for sale			1
Other current assets	15		19
Total current assets	433		402
Investment in unconsolidated entities	160		158
Deferred income taxes	0		0
Long-term assets held for sale			0
Other Assets, Noncurrent	14		17
Intercompany loans receivable	1,138		1,114
Property, Plant and Equipment, Net	382		410
Goodwill	52		52
Other intangible assets, net	25		32
Total assets	2,204		2,185
Current liabilities
Accounts and drafts payable	122		129
Intercompany accounts payable	28		80
Debt payable within one year	7		10
Intercompany loans payable within one year	0		22
Interest payable	99		80
Income taxes payable	5		6
Accrued payroll and incentive compensation	32		22
Current liabilities associated with assets held for sale			0
Other current liabilities	65		70
Total current liabilities	358		419
Long-term liabilities
Long-term debt	3,501		3,507
Intercompany loans payable	87		190
Accumulated losses of unconsolidated subsidiaries in excess of investment	854		668
Long-term pension and post employment benefit obligations	30		31
Deferred income taxes	2		2
Other long-term liabilities	111		109
Total liabilities	4,943		4,926
Total Hexion Inc. shareholder’s deficit	(2,739)		(2,741)
Noncontrolling interest	0		0
Total deficit	(2,739)		(2,741)
Total liabilities and deficit	2,204		2,185
Combined Subsidiary Guarantors [Member]
Current assets
Cash and cash equivalents (including restricted cash of $0 and $18, 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, Noncurrent	7		8
Intercompany loans receivable	0		0
Property, Plant and Equipment, Net	0		0
Goodwill	0		0
Other intangible assets, net	0		0
Total assets	22		22
Current liabilities
Accounts and drafts 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	174		171
Long-term pension and post employment benefit obligations	0		0
Deferred income taxes	0		0
Other long-term liabilities	0		0
Total liabilities	174		171
Total Hexion Inc. shareholder’s deficit	(152)		(149)
Noncontrolling interest	0		0
Total deficit	(152)		(149)
Total liabilities and deficit	22		22
Combined Non-Guarantor Subsidiaries [Member]
Current assets
Cash and cash equivalents (including restricted cash of $0 and $18, respectively)	94		102	111	168
Accounts receivable, net	375		335
Intercompany accounts receivable	28		80
Intercompany loans receivable - current portion	0		22
Finished and in-process goods	163		136
Raw materials and supplies	60		56
Current assets held for sale			5
Other current assets	41		25
Total current assets	761		761
Investment in unconsolidated entities	21		20
Deferred income taxes	8		8
Long-term assets held for sale			2
Other Assets, Noncurrent	25		24
Intercompany loans receivable	87		190
Property, Plant and Equipment, Net	518		514
Goodwill	61		60
Other intangible assets, net	9		10
Total assets	1,490		1,589
Current liabilities
Accounts and drafts payable	250		273
Intercompany accounts payable	136		121
Debt payable within one year	59		115
Intercompany loans payable within one year	8		1
Interest payable	2		2
Income taxes payable	7		6
Accrued payroll and incentive compensation	31		25
Current liabilities associated with assets held for sale			2
Other current liabilities	56		65
Total current liabilities	549		610
Long-term liabilities
Long-term debt	202		77
Intercompany loans payable	1,138		1,114
Accumulated losses of unconsolidated subsidiaries in excess of investment	0		0
Long-term pension and post employment benefit obligations	226		231
Deferred income taxes	9		9
Other long-term liabilities	69		68
Total liabilities	2,193		2,109
Total Hexion Inc. shareholder’s deficit	(702)		(519)
Noncontrolling interest	(1)		(1)
Total deficit	(703)		(520)
Total liabilities and deficit	1,490		1,589
Consolidation, Eliminations [Member]
Current assets
Cash and cash equivalents (including restricted cash of $0 and $18, respectively)	0		0	$ 0	$ 0
Accounts receivable, net	0		0
Intercompany accounts receivable	(164)		(201)
Intercompany loans receivable - current portion	(8)		(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	(172)		(224)
Investment in unconsolidated entities	(174)		(171)
Deferred income taxes	0		0
Long-term assets held for sale			0
Other Assets, Noncurrent	0		0
Intercompany loans receivable	(1,225)		(1,304)
Property, Plant and Equipment, Net	0		0
Goodwill	0		0
Other intangible assets, net	0		0
Total assets	(1,571)		(1,699)
Current liabilities
Accounts and drafts payable	0		0
Intercompany accounts payable	(164)		(201)
Debt payable within one year	0		0
Intercompany loans payable within one year	(8)		(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	(172)		(224)
Long-term liabilities
Long-term debt	0		0
Intercompany loans payable	(1,225)		(1,304)
Accumulated losses of unconsolidated subsidiaries in excess of investment	(1,028)		(839)
Long-term pension and post employment benefit obligations	0		0
Deferred income taxes	0		0
Other long-term liabilities	0		0
Total liabilities	(2,425)		(2,367)
Total Hexion Inc. shareholder’s deficit	854		668
Noncontrolling interest	0		0
Total deficit	854		668
Total liabilities and deficit	$ (1,571)		$ (1,699)