Goodwill and Intangible Assets - Definite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Jan. 31, 2021	Apr. 30, 2020
Definite-lived intangible assets
Gross Carrying Amount	$ 611,970	$ 592,098
Accumulated Amortization	339,571	291,581
Total	$ 272,399	$ 300,517
Customer relationships
Definite-lived intangible assets
Weighted Average Amortization Period (in years)	12 years 9 months 18 days	12 years 9 months 18 days
Gross Carrying Amount	$ 537,256	$ 516,928
Accumulated Amortization	314,191	270,029
Total	$ 223,065	$ 246,899
Customer relationships | Minimum
Definite-lived intangible assets
Estimated Useful Lives (years)	5 years	5 years
Customer relationships | Maximum
Definite-lived intangible assets
Estimated Useful Lives (years)	16 years	16 years
Tradenames
Definite-lived intangible assets
Weighted Average Amortization Period (in years)	16 years 3 months 18 days	16 years 3 months 18 days
Gross Carrying Amount	$ 58,203	$ 55,654
Accumulated Amortization	13,603	10,474
Total	$ 44,600	$ 45,180
Tradenames | Minimum
Definite-lived intangible assets
Estimated Useful Lives (years)	5 years	5 years
Tradenames | Maximum
Definite-lived intangible assets
Estimated Useful Lives (years)	20 years	20 years
Vendor agreements
Definite-lived intangible assets
Weighted Average Amortization Period (in years)	8 years 3 months 18 days	8 years 3 months 18 days
Gross Carrying Amount	$ 6,644	$ 6,644
Accumulated Amortization	5,171	4,567
Total	$ 1,473	$ 2,077
Vendor agreements | Minimum
Definite-lived intangible assets
Estimated Useful Lives (years)	8 years	8 years
Vendor agreements | Maximum
Definite-lived intangible assets
Estimated Useful Lives (years)	10 years	10 years
Developed technology
Definite-lived intangible assets
Estimated Useful Lives (years)	5 years	5 years
Weighted Average Amortization Period (in years)	4 years 10 months 24 days	4 years 10 months 24 days
Gross Carrying Amount	$ 5,477	$ 5,036
Accumulated Amortization	2,970	1,963
Total	$ 2,507	$ 3,073
Other intangible assets
Definite-lived intangible assets
Weighted Average Amortization Period (in years)	3 years 3 months 18 days	5 years 3 months 18 days
Gross Carrying Amount	$ 4,390	$ 7,836
Accumulated Amortization	3,636	4,548
Total	$ 754	$ 3,288
Other intangible assets | Minimum
Definite-lived intangible assets
Estimated Useful Lives (years)	3 years	1 year
Other intangible assets | Maximum
Definite-lived intangible assets
Estimated Useful Lives (years)	5 years	15 years