Investments in Companies Accounted for Using the Equity Method - Investment in Limited Partnership Fund (Details) - USD ($)			1 Months Ended			12 Months Ended
	Jan. 04, 2021	Jul. 15, 2020	May 31, 2022	Mar. 31, 2022	Jul. 31, 2019	Apr. 30, 2022	Apr. 30, 2021	Apr. 30, 2020
Equity Method Investments
Equity method investment income (loss), net of tax						$ 4,589,000	$ (10,481,000)	$ (5,487,000)
Carrying value of investment						15,433,000	7,168,000
Limited Partnership Fund
Equity Method Investments
Capital contributions	$ 2,675,000	$ 2,377,000	$ 2,774,000	$ 20,000,000	$ 4,948,000
Expected years contributions will be made				5 years
Additional capital contributions						0
Equity method investment income (loss), net of tax						5,889,000	49,000	(394,000)
Income tax expense from equity method investments						1,300,000	11	111,000
Limited Partnership Fund | Long term investments
Equity Method Investments
Carrying value of investment						15,433,000	7,168,000
HAPSMobile | Equity method investment loss, net of tax
Equity Method Investments
Equity method investment income (loss), net of tax						$ 0	$ 10,530,000	$ 4,982,000