v3.8.0.1

Fair Value of Financial Assets and Liabilities - Summary of Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands | Oct. 31, 2017 | Apr. 30, 2017
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Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | $ 51,988 | $ 52,494
Short-term investments: | 13,224 | 38,689
Fair value, measurements, recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 1,777 | 6,330
Short-term investments: | 13,224 | 38,689
Total assets | 15,001 | 45,019
Fair value, measurements, recurring | Fair value, inputs, level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 378 | 3,532
Short-term investments: | 5,242 | 25,418
Total assets | 5,620 | 28,950
Fair value, measurements, recurring | Fair value, inputs, level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 1,399 | 2,798
Short-term investments: | 7,982 | 13,271
Total assets | 9,381 | 16,069
Fair value, measurements, recurring | Fair value, inputs, level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 0 | 0
Short-term investments: | 0 | 0
Total assets | 0 | 0
Certificates of deposit | Fair value, measurements, recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 2,410 | 1,930
Certificates of deposit | Fair value, measurements, recurring | Fair value, inputs, level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 0 | 0
Certificates of deposit | Fair value, measurements, recurring | Fair value, inputs, level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 2,410 | 1,930
Certificates of deposit | Fair value, measurements, recurring | Fair value, inputs, level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 0 | 0
Commercial paper | Fair value, measurements, recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 1,399 | 2,798
Short-term investments: | 2,268 | 4,206
Commercial paper | Fair value, measurements, recurring | Fair value, inputs, level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 0 | 0
Short-term investments: | 0 | 0
Commercial paper | Fair value, measurements, recurring | Fair value, inputs, level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 1,399 | 2,798
Short-term investments: | 2,268 | 4,206
Commercial paper | Fair value, measurements, recurring | Fair value, inputs, level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 0 | 0
Short-term investments: | 0 | 0
U.S. Treasury securities | Fair value, measurements, recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 0 | 8,700
U.S. Treasury securities | Fair value, measurements, recurring | Fair value, inputs, level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 0 | 8,700
U.S. Treasury securities | Fair value, measurements, recurring | Fair value, inputs, level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 0 | 0
U.S. Treasury securities | Fair value, measurements, recurring | Fair value, inputs, level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 0 | 0
US government agencies debt securities | Fair value, measurements, recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 200 | 0
Short-term investments: | 5,242 | 16,718
US government agencies debt securities | Fair value, measurements, recurring | Fair value, inputs, level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 200 | 0
Short-term investments: | 5,242 | 16,718
US government agencies debt securities | Fair value, measurements, recurring | Fair value, inputs, level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 0 | 0
Short-term investments: | 0 | 0
US government agencies debt securities | Fair value, measurements, recurring | Fair value, inputs, level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 0 | 0
Short-term investments: | 0 | 0
Corporate debt securities | Fair value, measurements, recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 3,304 | 7,135
Corporate debt securities | Fair value, measurements, recurring | Fair value, inputs, level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 0 | 0
Corporate debt securities | Fair value, measurements, recurring | Fair value, inputs, level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 3,304 | 7,135
Corporate debt securities | Fair value, measurements, recurring | Fair value, inputs, level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Short-term investments: | 0 | 0
Money market funds | Fair value, measurements, recurring |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 178 | 3,532
Money market funds | Fair value, measurements, recurring | Fair value, inputs, level 1 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 178 | 3,532
Money market funds | Fair value, measurements, recurring | Fair value, inputs, level 2 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | 0 | 0
Money market funds | Fair value, measurements, recurring | Fair value, inputs, level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Cash equivalents: | $ 0 | $ 0

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- Definition Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258 + Details
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- Definition Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash -URI http://asc.fasb.org/extlink&oid=6506951 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Cash Equivalents -URI http://asc.fasb.org/extlink&oid=6507016 + Details
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- Definition Amount of investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(2)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)(g)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(5)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(6)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(4)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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