2. Cash, Cash Equivalents, Restricted Cash and Marketable Securities (Tables)

9 Months Ended

Feb. 28, 2019

Cash and Cash Equivalents [Abstract]

Schedule of fair value of cash, cash equivalents and investments in marketable securities

			Fair Value Measurements at February 28, 2019 Using
	Fair Value at February 28, 2019		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and cash equivalents:
Cash	$	53,051	$	53,051	$	–	$	–
Money market funds		713,110		713,110		–		–
Certificates of deposit		1,000,000		–		1,000,000		–
Restricted cash		198,887		198,887		–		–
Total	$	1,965,048	$	965,048	$	1,000,000	$	–

			Fair Value Measurements at May 31, 2018 Using
	Fair Value at May 31, 2018		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash and cash equivalents:
Cash	$	31,622	$	31,622	$	–	$	–
Money market funds		1,265,505		1,265,505		–		–
Certificates of deposit		1,000,763		–		1,000,763		–
Restricted cash		21,559		21,559		–		–
Total	$	2,319,449	$	1,318,686	$	1,000,763	$	–