Goodwill and Intangible Assets - Definite-Lived Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Definite lived intangible assets
Gross carrying amount	$ 306,606	$ 232,446
Accumulated amortization	115,681	72,024
Net carrying value	$ 190,925	$ 160,422
Customer relationships
Definite lived intangible assets
Weighted average amortization period	10 years 10 months 24 days	10 years 9 months 18 days
Gross carrying amount	$ 273,196	$ 208,526
Accumulated amortization	111,291	69,929
Net carrying value	$ 161,905	$ 138,597
Customer relationships | Minimum
Definite lived intangible assets
Estimated useful lives	5 years	5 years
Customer relationships | Maximum
Definite lived intangible assets
Estimated useful lives	13 years	13 years
Tradenames
Definite lived intangible assets
Weighted average amortization period	18 years 3 months 18 days	19 years 6 months
Gross carrying amount	$ 25,250	$ 15,760
Accumulated amortization	1,718	447
Net carrying value	$ 23,532	$ 15,313
Tradenames | Minimum
Definite lived intangible assets
Estimated useful lives	5 years	5 years
Tradenames | Maximum
Definite lived intangible assets
Estimated useful lives	20 years	20 years
Vendor agreement
Definite lived intangible assets
Estimated useful lives	8 years	8 years
Gross carrying amount	$ 5,644	$ 5,644
Accumulated amortization	2,176	1,470
Net carrying value	$ 3,468	$ 4,174
Leasehold interests
Definite lived intangible assets
Weighted average amortization period	8 years 2 months 12 days	8 years 2 months 12 days
Gross carrying amount	$ 2,516	$ 2,516
Accumulated amortization	496	178
Net carrying value	$ 2,020	$ 2,338
Leasehold interests | Minimum
Definite lived intangible assets
Estimated useful lives	7 years	7 years
Leasehold interests | Maximum
Definite lived intangible assets
Estimated useful lives	13 years	13 years