Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Apr. 30, 2016 USD ($) Segment Facility	Apr. 30, 2015 USD ($) shares	Apr. 30, 2014 USD ($) shares	May 05, 2014 USD ($)
Product Information [Line Items]
Maximum maturity period of all highly liquid investments to be considered cash equivalents	3 months
Fair value of the interest rate swap liability	$ 1,300,000
Number of reportable segments | Segment	2
Number of reporting units | Facility	2
Goodwill	$ 76,357,000	$ 75,426,000
Remaining cost related to recalls and safety alerts costs	4,000,000
Warranty expense	2,500,000	4,300,000	$ 3,600,000
Promotional programs amount	20,700,000	6,900,000	1,600,000
Selling and marketing expenses	6,500,000	2,800,000	$ 1,900,000
Decrease in other assets and other long-term liabilities as a result of adopting ASU		$ 4,100,000
Self Insurance
Product Information [Line Items]
Maximum amount of self-insurance per occurrence	10,000,000
DRP Acquisition
Product Information [Line Items]
Goodwill	13,800,000			$ 13,770,000
BTI Acquisition and Subsequent Acquisition by BTI
Product Information [Line Items]
Goodwill	$ 62,600,000
2011 ESPP
Product Information [Line Items]
Number of common stock issuable with antidilutive effect | shares		73,546	77,622
Other Capitalized Property Plant and Equipment | Maximum
Product Information [Line Items]
Estimated useful life	5 years
Customer One | Sales, net
Product Information [Line Items]
Concentration of risk, percentage	10.00%	10.00%	13.40%
Customer One | Accounts Receivable
Product Information [Line Items]
Concentration of risk, percentage	10.00%	10.00%
5.000% Senior Notes due 2018
Product Information [Line Items]
Debt instrument, interest rate	5.00%	5.00%
(Level 2) | Interest Rate Swap
Product Information [Line Items]
Fair value of the interest rate swap liability	$ 1,300,000