Long-Term Debt - Acquisition Debt (Details) - USD ($) $ in Thousands						3 Months Ended
	Jun. 07, 2017	Nov. 18, 2016	Sep. 27, 2016	Jun. 01, 2016	Apr. 01, 2014	Jul. 31, 2017	Jul. 31, 2016
Long-term debt
Repayment of amounts outstanding under credit facility						$ 257,382	$ 225,702
Net amount of debt issued						577,616
Cash paid for interest						6,792	6,613
Write-off of debt discount and deferred financing fees						74	5,426
Term Loan Facilities, April 1, 2014
Long-term debt
Face amount of debt					$ 550,000
First Lien Term Loan due 2021
Long-term debt
Net amount of debt issued					388,050
Original issue discount					1,950
Loan repayment	$ 477,616
Second Lien Term Loan due 2022
Long-term debt
Net amount of debt issued					158,400
Original issue discount					$ 1,600
Loan repayment				$ 160,000			$ 160,000
Write-off of debt discount and deferred financing fees				$ 5,426
Incremental First Lien Term Commitments Amendment
Long-term debt
Face amount of debt			$ 481,225
Reduction to interest rate margin at each pricing level (as a percent)			(25.00%)
Loan repayment			$ 381,225
Write-off of debt discount and deferred financing fees			$ 1,466
Incremental First Lien Term Commitments Amendment | LIBOR
Long-term debt
Variable rate floor (as a percent)			1.00%
Margin added to variable rate (as a percent)			3.50%
Second amendment to First Lien Credit Agreement
Long-term debt
Face amount of debt	$ 577,616
Reduction to interest rate margin at each pricing level (as a percent)	(50.00%)
Loan repayment						$ 477,616
Second amendment to First Lien Credit Agreement | LIBOR
Long-term debt
Variable rate floor (as a percent)	1.00%
Margin added to variable rate (as a percent)	3.00%
ABL Facility
Long-term debt
Loan repayment	$ 94,000
ABL Second Amendment
Long-term debt
Reduction to interest rate margin at each pricing level (as a percent)		0.25%