Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Property, Plant and Equipment [Abstract]
Depreciation and amortization expense related to property and equipment	$ 14.6	$ 18.1

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