SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition - Product revenue (Details)	6 Months Ended
Jun. 30, 2022
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Discount for prompt payment (as a percent)	2.00%

The discount percentage generally provided for sales to distributors for prompt payment.

No definition available.

Name:	ymab_PaymentTermsDiscountForPromptPaymentPercent
Namespace Prefix:	ymab_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration