Revenue - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue
Amount of compensation to distributors included in sales rebates	$ 0	$ 0	$ 22,009	$ 0

Revenue from contract with customer adjustments for compensation to distributors .

No definition available.

Name:	zlab_RevenueFromContractWithCustomerAdjustmentsForCompensationToDistributors
Namespace Prefix:	zlab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration