Goodwill and Intangible Assets - Amortization (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Intangible assets
Amortization expense related to intangible assets	$ 10,820	$ 8,797	$ 20,233	$ 17,589
Depreciation and amortization expense
Intangible assets
Amortization expense related to intangible assets	$ 10,820	$ 8,797	$ 20,233	$ 17,589