Long-Term Debt - Components (Details) - USD ($) $ in Thousands	Jan. 31, 2017	Apr. 30, 2016
Long-term debt
Total long-term debt	$ 612,279	$ 644,610
Less: Current portion	11,235	35,581
Long-term debt, less current portion	601,044	609,029
First Lien Term Loan due 2021
Long-term debt
Total long-term debt	470,978	373,998
Unamortized discount	1,764	1,355
Deferred financing costs	6,077	6,847
Second Lien Term Loan due 2022
Long-term debt
Total long-term debt		154,517
Unamortized discount		1,183
Deferred financing costs		4,300
ABL Facility
Long-term debt
Total long-term debt	120,821	101,910
Capital lease obligations
Long-term debt
Total long-term debt	$ 14,283	$ 11,449
Interest rate	5.50%	5.50%
Installment notes
Long-term debt
Total long-term debt	$ 6,197	$ 2,736
Installment notes | Maximum
Long-term debt
Interest rate	2.70%	2.70%