Revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Jul. 31, 2021	Jul. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenue earned, deferred revenue	$ 6.8	$ 3.7
Revenue Benchmark \| Non-US \| Customer Concentration Risk
Disaggregation of Revenue [Line Items]
Percentage of revenues from students outside the United States	1.00%	1.00%

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
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Data Type:	dtr-types:percentItemType
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Period Type:	duration