For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13531-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13537-108611

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Basis of presentation and significant accounting policies (Details) - USD ($)	1 Months Ended	3 Months Ended		12 Months Ended
	Sep. 30, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Concentration Risk [Line Items]
Asset impairment charges	$ 0
Four customers \| Revenue
Concentration Risk [Line Items]
Percentage of concentration of credit risk		10.00%
Four customers \| Accounts Receivable
Concentration Risk [Line Items]
Percentage of concentration of credit risk		72.00%
Top five customers \| Revenue
Concentration Risk [Line Items]
Percentage of concentration of credit risk		80.00%	85.00%
Huawei \| Revenue
Concentration Risk [Line Items]
Percentage of concentration of credit risk			52.00%
One customer \| Revenue
Concentration Risk [Line Items]
Percentage of concentration of credit risk			10.00%
Three customers \| Accounts Receivable
Concentration Risk [Line Items]
Percentage of concentration of credit risk				65.00%