Fresh Start Accounting Schedule of Fresh Start Adjustments to the Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jul. 01, 2019
Fresh-Start Adjustment [Line Items]
Cash and Cash Equivalents		$ 29
Common stock (Predecessor)		(1)
Cancellation of Predecessor treasury stock		296
Accumulated deficit		1,840
Noncontrolling interest		(1)
Pension Obligations		(239)
Additional Paid-in Capital	$ 1,162	1,157
Inventory fair value adjustments		29
Property, plant and equipment fair value adjustment		780
Repayment of DIP Term Loan interest		(5)
Fresh-Start Adjustment, Increase (Decrease), Pension Obligations		44
Cash and Cash Equivalents		125
Establishment of Successor goodwill		178
Common stock (Successor)	$ 0
Total equity (deficit)		1,156
Total liabilities and equity (deficit)		4,292
Reorganization Adjustments
Fresh-Start Adjustment [Line Items]
Cash and Cash Equivalents		29
Accounts Receivable		0
Finished and in-process goods		0
Raw materials and supplies		0
Other current assets		2
Total current assets		31
Investment in unconsolidated entities		0
Deferred tax assets		12
Other long-term assets		4
Land		0
Buildings		0
Machinery and equipment		0
Property and equipment, gross		0
Accumulated Depreciation and Amortization		0
Property and Equipment, Net		0
Operating lease assets		0
Other intangible assets, net		0
Total assets		47
Accounts payable		56
Debt payable within one year		(343)
Income taxes payable		11
Accrued payroll and incentive compensation		0
Current portion of operating lease liabilities		0
Financing fees payable		(104)
Other current liabilities		5
Total current liabilities		(380)
Liabilities subject to compromise		(3,672)
Long-term debt		1,622
Long-term pension and post employment benefit obligations		33
Deferred income taxes		1
Operating lease liabilities		0
Other long-term liabilities		72
Total liabilities		(2,324)
Common stock (Predecessor)		(1)
Paid-in capital (Predecessor)		1,157
Cancellation of Predecessor treasury stock		296
Elimination of Predecessor Company accumulated other comprehensive income		0
Accumulated deficit		1,445
Total Hexion Inc. equity (deficit)		2,371
Noncontrolling interest		0
Total equity (deficit)		2,371
Total liabilities and equity (deficit)		47
Predecessor Paid-in-capital		(526)
Repayment of DIP Term Loan interest		(5)
Fresh Start Adjustments
Fresh-Start Adjustment [Line Items]
Fresh-start adjustment, increase (decrease), noncontrolling interest		0
Accumulated deficit		1,840
Accumulated other comprehensive loss		26
Cancellation of Predecessor treasury stock		0
Cancellation of Predecessor additional paid-in capital		0
Fresh-Start Adjustment, Increase (Decrease), Cash and Cash Equivalents		0
Fresh-Start Adjustment, Increase (Decrease), Receivables, Net		6
Inventory fair value adjustments		29
Fresh-start adjustment increase (decrease) raw materials		0
Fresh-Start Adjustment, Increase (Decrease), Prepaid and Other Current Assets		0
Fresh-Start Adjustment, Increase (Decrease), Current Assets		35
Fresh-start adjustment increase (decrease) investment in and advancement to affiliate		(3)
Fresh-Start Adjustment, Increase (Decrease), Deferred Income Tax Assets, Noncurrent		(4)
Fresh-Start Adjustment, Increase (Decrease), Other Assets, Noncurrent		2
Fresh-Start Adjustment, Increase (Decrease), Land		23
Fresh-Start Adjustment, Increase (Decrease), Buildings and Improvements		(119)
Fresh-Start Adjustment, Increase (Decrease), Equipment		(994)
Fresh-start adjustment increase (decrease), Property and Equipment, Gross		(1,090)
Fresh-Start Adjustment, Increase (Decrease), Accumulated Depreciation and Amortization		1,870
Property, plant and equipment fair value adjustment		780
Fresh-start adjustment, increase (decrease), Operating Lease, Right of Use Asset		39
Fresh-Start Adjustment, Increase (Decrease), Goodwill		70
Fresh-Start Adjustment, Increase (Decrease), Amortizable Intangible Assets		1,195
Fresh-Start Adjustment, Increase (Decrease), Assets		2,114
Fresh-Start Adjustment, Increase (Decrease), Accounts Payable		0
Fresh-Start Adjustment, Increase (Decrease), Current Maturities of Long-term Debt		2
Fresh-start adjustment, increase (decrease), Interest Payable		0
Fresh-Start Adjustment, Increase (Decrease), Deferred Income Tax Liabilities, Current		0
Fresh-start adjustment, increase (decrease), Employee relared Liabilities, current		0
Fresh-start adjustment, increase (decrease), Operating lease liability, current		7
Fresh-start adjustment, increase (decrease), Financing Fees Payable		0
Fresh-Start Adjustment, Increase (Decrease), Other Current Liabilities		0
Fresh-Start Adjustment, Increase (Decrease), Current Liabilities		9
Fresh-Start Adjustment, Increase (Decrease), Liabilities Subject to Compromise		0
Fresh-Start Adjustment, Increase (Decrease), Long-term Debt		21
Fresh-Start Adjustment, Increase (Decrease), Pension Obligations		44
Fresh-Start Adjustment, Increase (Decrease), Deferred Income Tax Liabilities, Noncurrent		163
Fresh-start adjustment, increase (decrease), Operating lease liability, Noncurrent		17
Fresh-Start Adjustment, Increase (Decrease), Other Noncurrent Obligations		(6)
Fresh-Start Adjustment, Increase (Decrease), Liabilities		248
Cancellation of Predecessor common stock		0
Fresh-start Adjsutment, Incrrease (decrease), Equity attributable to Parent		1,866
Fresh-Start adjustment, Increase (Decrease), Stockholders Equity, Including portion attributable to non-controlling interest		1,866
Fresh-Start Adjustment, Increase (Decrease), Liabilities and Stockholders' Equity		2,114
Predecessor Company [Member]
Fresh-Start Adjustment [Line Items]
Cash and Cash Equivalents		96
Accounts Receivable		499
Finished and in-process goods		242
Raw materials and supplies		109
Other current assets		69
Total current assets		1,015
Investment in unconsolidated entities		20
Deferred tax assets		0
Other long-term assets		42
Land		90
Buildings		287
Machinery and equipment		2,320
Property and equipment, gross		2,697
Accumulated Depreciation and Amortization		(1,870)
Property and Equipment, Net		827
Operating lease assets		95
Goodwill		(108)
Other intangible assets, net		24
Total assets		2,131
Accounts payable		293
Debt payable within one year		438
Interest payable		7
Income taxes payable		6
Accrued payroll and incentive compensation		38
Current portion of operating lease liabilities		21
Financing fees payable		104
Other current liabilities		106
Total current liabilities		1,013
Liabilities subject to compromise		3,672
Long-term debt		90
Long-term pension and post employment benefit obligations		184
Deferred income taxes		15
Operating lease liabilities		74
Other long-term liabilities		164
Total liabilities		5,212
Common stock (Predecessor)		1
Paid-in capital (Predecessor)		526
Cancellation of Predecessor treasury stock		296
Elimination of Predecessor Company accumulated other comprehensive income		(26)
Accumulated deficit		(3,285)
Total Hexion Inc. equity (deficit)		(3,080)
Noncontrolling interest		(1)
Total equity (deficit)		(3,081)
Total liabilities and equity (deficit)		2,131
Successor Company [Member]
Fresh-Start Adjustment [Line Items]
Noncontrolling interest		(1)
Additional Paid-in Capital		1,157
Cash and Cash Equivalents		125
Receivables, Net		505
Finished and in-process goods		271
Raw materials and supplies		109
Other current assets		71
Total current assets		1,081
Investment in unconsolidated entities		17
Deferred tax assets		8
Other long-term assets		48
Land		113
Buildings		168
Machinery and equipment		1,326
Property and Equipment Gross		1,607
Accumulated Depreciation and Amortization		0
Property and Equipment, Net		1,607
Operating lease assets		134
Establishment of Successor goodwill		178
Other intangible assets, net		1,219
Total assets		4,292
Accounts payable		349
Debt payable within one year		97
Interest payable		2
Income taxes payable		17
Accrued payroll and incentive compensation		38
Current portion of operating lease liabilities		28
Financing fees payable		0
Other current liabilities		111
Total current liabilities		642
Liabilities subject to compromise		0
Long-term debt		1,733
Long-term pension and post employment benefit obligations		261
Deferred income taxes		179
Operating lease liabilities		91
Other long-term liabilities		230
Total liabilities		3,136
Common stock (Successor)		0
Total Hexion Inc. equity (deficit)		1,157
Total equity (deficit)		1,156
Total liabilities and equity (deficit)		$ 4,292