Summary of Significant Accounting Policies - Accrual for loss contracts (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accrual for loss contracts
Beginning Balance	$ 3,702	$ 5,345
Provision (benefit) for Loss Accrual	35,473	394	$ 5,345
Released to Service Cost of Sales	(2,348)	(1,249)
Released to Provision for Warrants	(12,814)
Ending Balance	$ 24,013	$ 3,702	$ 5,345

Amount charged against operating income increasing loss contingency liability, after adjustments to reduce previously estimated charges.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14326-108349

Name:	us-gaap_LossContingencyAccrualProvision
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration