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://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 2: 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=118260190&loc=d3e13531-108611

Reference 3: 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=118260190&loc=d3e13537-108611

Reference 4: 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

Summary of business and significant accounting policies - Concentration of Risk and Significant Customers (Details) - Customer Concentration Risk	3 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019
Ford Motor Company \| Sales Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	54.00%	67.00%
Ford Motor Company \| Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	42.00%		33.00%
GM \| Sales Revenue
Concentration Risk [Line Items]
Concentration risk, percentage	25.00%	16.00%
GM \| Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	23.00%		15.00%
Xevo Inc \| Accounts Receivable
Concentration Risk [Line Items]
Concentration risk, percentage	13.00%		29.00%