10. Commitments and Contingencies (Details) - Contingent Consideration - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Project Acquisition, Contingent Consideration Liability, Current	$ 2.0	$ 2.4
Project Acquisition, Contingent Consideration Liability, Noncurrent	$ 4.5	$ 4.5

Project Acquisition, Contingent Consideration Liability, Noncurrent

No definition available.

Name:	fslr_ProjectAcquisitionContingentConsiderationLiabilityNoncurrent
Namespace Prefix:	fslr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant