Investments (Details Narrative) - USD ($)	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Impairment loss	$ 68,000	$ 31,000
Reclassified net unrealized gains on marketable securities	$ 2,424,000
Minimum [Member]
Available-for-sale debt securities maturity year	2019-06
Maximum [Member]
Available-for-sale debt securities maturity year	2044-11