Summary of Significant Accounting Policies, Recently Issued and Recently Adopted Accounting Standards (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016
Book Overdrafts [Abstract]
Book overdrafts	$ 13,100	$ 17,600
Allowance for Doubtful Accounts [Abstract]
Allowance for doubtful accounts	10,100	7,200
Inventories [Abstract]
LIFO inventories	24,000	31,500
Reserve for Inventory Obsolescence [Abstract]
Inventory obsolescence reserve	18,200	21,100
Shipping and Handling Costs [Abstract]
Shipping and handling costs	33,700	39,100	$ 40,500
Advertising Expense [Abstract]
Advertising costs	68,300	$ 61,400	$ 54,100
Foreign Currency Gains/Losses [Abstract]
Foreign currency translation gains	$ 67,600
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in diluted shares outstanding (in shares)	845	862	736
Excess tax benefits recorded in operating activities	$ 0	$ (414)	$ (1,027)
Excess tax benefits recorded in financing activities	0	414	$ 1,027
Allowance for Sales Returns [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Increase (Decrease) in net assets	(18,628)	(24,300)
Allowance for Sales Returns [Member] | Accounts Receivable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Increase (Decrease) in net assets	(28,302)	(34,769)
Allowance for Sales Returns [Member] | Inventories [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Increase (Decrease) in net assets	4,626	4,727
Allowance for Sales Returns [Member] | Royalties Payable [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Increase (Decrease) in net assets	$ (5,048)	(5,741)
Book Composition Costs [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	1 year
Book Composition Costs [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Other Product Development Costs [Member] | Weighted Average [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	6 years
Computer Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Computer Hardware [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Computer Hardware [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Building and Leasehold Improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years
Furniture, Fixtures and Warehouse Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Furniture, Fixtures and Warehouse Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Software Development [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Software Development [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	6 years
Enterprise Resource Planning and Related Systems [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life	10 years
Content and Publishing Rights [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	2 years
Content and Publishing Rights [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	40 years
Content and Publishing Rights [Member] | Weighted Average [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	30 years
Trademarks [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	2 years
Trademarks [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	40 years
Trademarks [Member] | Weighted Average [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	15 years
Customer Relationships [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	2 years
Customer Relationships [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	40 years
Customer Relationships [Member] | Weighted Average [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	20 years
Brands [Member] | Minimum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	2 years
Brands [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	40 years
Brands [Member] | Weighted Average [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	15 years
Non-compete Agreements [Member] | Maximum [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	5 years
Non-compete Agreements [Member] | Weighted Average [Member]
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	5 years
Performance-based Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target period for stock-based compensation expense in advance of actual financial results	3 years
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Amounts netted down from accounts receivable and deferred revenue	$ 59,500
Accounting Standards Update 2015-17 [Member] | Prepaid and Other Current Assets [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred tax assets, current		800
Accounting Standards Update 2016-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Excess income tax benefits from stock-based compensation	1,600
Excess tax benefits recorded in operating activities	$ 0
Excess tax benefits recorded in financing activities		400
Accounting Standards Update 2016-09 [Member] | Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase in diluted shares outstanding (in shares)	100
Accounting Standards Update 2017-07 Member] | Plan [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net charges expected to be reclassified from operating income to a line item below operating income	$ 8,100	$ 5,300