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Fair Value Measurements - Narrative (Details) - USD ($) | Feb. 28, 2019 | May 31, 2018
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Fair Value Disclosures [Abstract] |  |
Marketable securities | $ 0 | $ 0

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- Definition Amount of investment in marketable security. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -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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