ACCRUED LIABILITIES (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Accrued short-term liabilities
Accrued licensing, milestone and royalty payments	$ 2,438	$ 3,090
Accrued clinical costs	872	915
Accrued compensation and board fees	4,151	1,877
Accrued manufacturing costs	6,251	2,622
Accrued sales reserves	3,082	2,615
Other	273	1,421
Total	$ 17,067	$ 12,540

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.20)
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Period Type:	instant

- References

No definition available.

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- Definition

Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.

+ References

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- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for clinical costs. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for compensation and board fees. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

No definition available.

+ Details

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Namespace Prefix:	ymab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for licensing, milestones and royalties. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

No definition available.

+ Details

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Namespace Prefix:	ymab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for manufacturing costs. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

No definition available.

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- Definition

Carrying value as of the balance sheet date of obligations incurred through that date and payable for sales reserves. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

+ References

No definition available.

+ Details

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Namespace Prefix:	ymab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant