Property and Equipment - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Property Plant And Equipment [Abstract]
Depreciation and amortization expense related to property and equipment	$ 3.0	$ 1.6	$ 5.2	$ 3.1

Depreciation and amortization of property and equipment.

No definition available.

Name:	qs_DepreciationAndAmortizationOfPropertyAndEquipment
Namespace Prefix:	qs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration