Acquisition of RSI Home Products, Inc. (the "RSI Acquisition") (Narrative) (Details) - USD ($)		3 Months Ended								4 Months Ended	12 Months Ended
	Dec. 29, 2017	Apr. 30, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018	Feb. 12, 2018	May 01, 2016
Business Acquisition [Line Items]
Cash consideration, net of cash acquired											$ 0	$ 7,182,000	$ 57,200,000
Goodwill, net		$ 767,612,000				$ 767,612,000					767,612,000	767,612,000
Customer receivables	$ 57,100,000
Allowance for returns and discounts	2,400,000
Net sales		399,197,000	$ 395,755,000	$ 428,016,000	$ 427,365,000	407,399,000	$ 384,080,000	$ 424,878,000	$ 428,962,000		1,650,333,000	1,645,319,000	1,250,274,000
Operating profit											132,262,000	141,694,000	107,705,000
Charge to cost of sales as a result of the step up of inventory											$ 1,321,147,000	$ 1,298,846,000	994,871,000
Transaction costs													$ 8,500,000
Statutory tax rate											21.00%	21.00%	30.40%
Amortization expense, net of tax													$ 20,000,000.0
Interest expense, net of tax													2,400,000
RSI Home Products, Inc. [Member]
Business Acquisition [Line Items]
Indebtedness assumed (including accrued interest)	589,000,000
Total accounting consideration paid	554,232,000
Cash consideration, net of cash acquired	$ 364,400,000
Newly issued shares (shares)	1,457,568
Value of newly issued common stock	$ 189,800,000
Price per share (usd per share)	$ 130.25
Goodwill, net	$ 767,612,000
Allowance for doubtful accounts	100,000
Net sales										$ 177,700,000
Operating profit										9,100,000
Transaction costs													12,900,000
Senior Notes [Member] | RSI Home Products, Inc. [Member]
Business Acquisition [Line Items]
Debt issued														$ 350,000,000
Revolving Credit Facility [Member]
Business Acquisition [Line Items]
Proceeds from term loan	50,000,000
Borrowed under the Credit Agreement		0				0					$ 0	$ 0
Revolving Credit Facility [Member] | RSI Home Products, Inc. [Member]
Business Acquisition [Line Items]
Proceeds from term loan	50,000,000
Revolving Credit Facility [Member] | Revolving Facility [Member] | RSI Home Products, Inc. [Member]
Business Acquisition [Line Items]
Line of credit facility, maximum borrowing capacity	100,000,000
Revolving Credit Facility [Member] | Credit Agreement [Member]
Business Acquisition [Line Items]
Borrowed under the Credit Agreement															$ 300,000,000
Letter of Credit [Member] | Revolving Facility [Member] | RSI Home Products, Inc. [Member]
Business Acquisition [Line Items]
Line of credit facility, maximum borrowing capacity	25,000,000
Loans Payable [Member] | Initial Term Loan [Member]
Business Acquisition [Line Items]
Debt issued	250,000,000
Borrowed under the Credit Agreement		122,000,000				170,000,000					122,000,000	170,000,000
Loans Payable [Member] | Initial Term Loan [Member] | RSI Home Products, Inc. [Member]
Business Acquisition [Line Items]
Line of credit facility, maximum borrowing capacity	$ 250,000,000
Loan facility term	5 years
Loans Payable [Member] | Delayed Draw Term Loan [Member]
Business Acquisition [Line Items]
Debt issued	$ 250,000,000
Borrowed under the Credit Agreement		$ 170,000,000				$ 230,000,000					$ 170,000,000	$ 230,000,000
Loans Payable [Member] | Delayed Draw Term Loan [Member] | RSI Home Products, Inc. [Member]
Business Acquisition [Line Items]
Line of credit facility, maximum borrowing capacity	$ 250,000,000
Fair Value Adjustment to Inventory [Member] | RSI Home Products, Inc. [Member]
Business Acquisition [Line Items]
Charge to cost of sales as a result of the step up of inventory										$ 6,300,000			$ 4,100,000
Pro Forma [Member]
Business Acquisition [Line Items]
Statutory tax rate													34.40%