Goodwill and Intangible Assets - Amortization (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Intangible assets
Amortization expense	$ 19,249	$ 10,690	$ 34,961	$ 21,045
Depreciation and amortization expense
Intangible assets
Amortization expense	$ 19,200	$ 10,700	$ 35,000	$ 21,000