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=109250915&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=109250915&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

Credit Concentration (Details)	12 Months Ended
Credit Concentration (Details)	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Accounts Receivable [Member] \| Customer A [Member]
Concentration Risk [Line Items]
Concentration risk percentage	28.20%	30.80%
Accounts Receivable [Member] \| Customer B [Member]
Concentration Risk [Line Items]
Concentration risk percentage	25.90%	25.50%
Sales Revenue, Gross [Member] \| Customer A [Member]
Concentration Risk [Line Items]
Concentration risk percentage	29.30%	23.50%	18.50%
Sales Revenue, Gross [Member] \| Customer B [Member]
Concentration Risk [Line Items]
Concentration risk percentage	18.60%	16.00%	15.70%