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Acquisitions and Strategic Agreements Acquisitions and Strategic Agreements (MBS Details) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 28, 2018	Apr. 29, 2017	Apr. 30, 2016
Business Acquisition, Pro Forma Revenue		$ 2,247,825	$ 2,216,628
Goodwill, Acquired During Period		48,556
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual		34,091
Business Combination, Pro Forma Information, Earnings or Loss of Acquiree since Acquisition Date, Actual		(2,630)
Business Acquisition, Pro Forma Net Income (Loss)		$ 32,055	$ 25,022
Goodwill, Purchase Accounting Adjustments	$ 1,163
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Consideration Transferred	888
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities	275
MBS [Member]
Business Acquisition, Percentage of Voting Interests Acquired		100.00%
Business Combination, Consideration Transferred		$ 187,862
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Cash and Equivalents		1,171
Business Combination, Consideration Transferred, Liabilities Incurred		15,556
Business Combination, Consideration Transferred, Other		(21,674)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Other		472
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Receivables		28,177
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Inventory		128,431
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment		12,403
Finite-lived Intangible Assets Acquired		21,576
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Assets, Prepaid Expense and Other Assets		4,748
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets		195,807
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Accounts Payable		35,383
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities, Other		8,799
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Noncurrent Liabilities, Other		13,045
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		57,227
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net		138,580
Goodwill, Acquired During Period		49,282
Goodwill, Purchase Accounting Adjustments	$ 1,163
Cash paid to seller or escrow [Member] \| MBS [Member]
Payments to Acquire Businesses, Gross		165,499
Consideration to seller for pre-closing costs [Member] \| MBS [Member]
Payments to Acquire Businesses, Gross		4,657
Cash paid for seller closing costs [Member] \| MBS [Member]
Payments to Acquire Businesses, Gross		4,044
contract purchase price [Member] \| MBS [Member]
Payments to Acquire Businesses, Gross		174,200
Payment to settle Seller's outstanding short-term borrowings [Member] \| MBS [Member]
Payments to Acquire Businesses, Gross		24,437
Off-Market Favorable Lease [Member] \| MBS [Member]
Finite-lived Intangible Assets Acquired		$ 1,076
Finite-Lived Intangible Asset, Useful Life		6 years 6 months
Trade Names [Member] \| MBS [Member]
Finite-lived Intangible Assets Acquired		$ 3,500
Finite-Lived Intangible Asset, Useful Life		10 years
Technology-Based Intangible Assets [Member] \| MBS [Member]
Finite-lived Intangible Assets Acquired		$ 1,500
Finite-Lived Intangible Asset, Useful Life		3 years
Book Store Relationship [Member] \| MBS [Member]
Finite-lived Intangible Assets Acquired		$ 13,000
Finite-Lived Intangible Asset, Useful Life		13 years
Customer Relationships [Member] \| MBS [Member]
Finite-lived Intangible Assets Acquired		$ 2,000
Finite-Lived Intangible Asset, Useful Life		15 years
Noncompete Agreements [Member] \| MBS [Member]
Finite-lived Intangible Assets Acquired		$ 500
Finite-Lived Intangible Asset, Useful Life		3 years