Long-Term Debt - Acquisition Debt (Details)					7 Months Ended	12 Months Ended
	Jun. 07, 2017 USD ($)	Sep. 27, 2016 USD ($)	Jun. 01, 2016 USD ($)	Apr. 01, 2014 USD ($)	Apr. 30, 2017 USD ($)	Apr. 30, 2017 USD ($) loan	Apr. 30, 2016 USD ($)	Apr. 30, 2015 USD ($)
Long-term debt
Repayment of amounts outstanding under credit facility						$ 1,011,925,000	$ 697,144,000	$ 303,099,000
Net amount of debt issued						481,225,000
Accrued interest					$ 721,000	721,000	678,000
Cash paid for interest						26,443,000	34,557,000	31,720,000
Term Loan Facilities, April 1, 2014
Long-term debt
Face amount of debt				$ 550,000,000
Cash paid for interest						21,567,000	32,130,000	$ 30,251,000
Term Loan Facilities, April 1, 2014 | Other accrued expenses and current liabilities
Long-term debt
Accrued interest							246,000
First Lien Term Loan due 2021
Long-term debt
Net amount of debt issued				388,050,000
Original issue discount				1,950,000	$ 1,658,000	$ 1,658,000	1,355,000
Borrowing interest rate (as a percent)					4.67%	4.67%
Loan repayment		$ 381,225,000
Loan amortization installment frequency						quarterly
Loan amortization installments						$ 1,444,000
Loan amortization installments (as a percent)						0.25%
First Lien Term Loan due 2021 | Minimum
Long-term debt
Number of incremental loans | loan						1
First Lien Term Loan due 2021 | Maximum
Long-term debt
Fixed amount of incremental loan						$ 100,000,000
First Lien Term Loan due 2021 | LIBOR
Long-term debt
Margin added to variable rate (as a percent)						3.00%
First Lien Term Loan due 2021 | Other accrued expenses and current liabilities
Long-term debt
Accrued interest					$ 181,000	$ 181,000
Second Lien Term Loan due 2022
Long-term debt
Net amount of debt issued				158,400,000
Original issue discount				1,600,000	$ 0	0	1,183,000
Loan repayment			$ 160,000,000			160,000,000
Incremental First Lien Term Commitments Amendment
Long-term debt
Face amount of debt		$ 481,225,000
Reduction to interest rate margin at each pricing level (as a percent)		(25.00%)
Loan repayment						381,225,000
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%			3.50%
2010 Credit Facility
Long-term debt
Repayment of amounts outstanding under credit facility				$ 86,120,000
ABL Facility
Long-term debt
Accrued interest					$ 532,000	$ 532,000	$ 422,000
ABL Second Amendment
Long-term debt
Reduction to interest rate margin at each pricing level (as a percent)						0.25%
Subsequent Event | First Lien Term Loan due 2021
Long-term debt
Loan repayment	$ 477,616,000
Subsequent Event | Second amendment to First Lien Credit Agreement
Long-term debt
Net amount of debt issued	$ 577,615,000
Subsequent Event | 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%
Subsequent Event | ABL Facility
Long-term debt
Repayment of amounts outstanding under credit facility	$ 94,000,000