Acquisitions (Details) $ in Thousands	12 Months Ended
	Apr. 30, 2016 USD ($) store Counterparty	Apr. 25, 2015 USD ($) Counterparty	Apr. 26, 2014 USD ($) Counterparty
Acquisitions
Cash paid	$ 23,311	$ 1,774	$ 801
Goodwill	$ 37,193	$ 15,164	$ 13,923
Independent dealer assets acquired in fiscal 2016
Acquisitions
Number of dealers whose assets were acquired | Counterparty	4
Number of stores | store	11
Total purchase price	$ 26,300
Cash paid	23,300
Prepaid expenses and forgiveness of accounts and notes receivable	3,000
Settlement gain or loss	0
Goodwill	22,000
Fair values at the dates of acquisition
Current assets	4,146
Goodwill and other intangible assets	25,129
Net property, plant, and equipment	202
Total assets acquired	29,477
Current liabilities	(3,217)
Net assets acquired	26,260
Independent dealer assets acquired in fiscal 2016 | Reacquired rights
Acquisitions
Indefinite-lived intangible asset	$ 3,100
Independent dealer assets acquired in fiscal 2015
Acquisitions
Number of dealers whose assets were acquired | Counterparty		2
Cash paid		$ 1,800
Prepaid expenses and forgiveness of accounts and notes receivable		1,000
Goodwill		1,200
Independent dealer assets acquired in fiscal 2015 | Reacquired rights
Acquisitions
Indefinite-lived intangible asset		$ 1,000
Independent dealer assets acquired in fiscal 2014
Acquisitions
Number of dealers whose assets were acquired | Counterparty			2
Cash paid			$ 800
Prepaid expenses and forgiveness of accounts and notes receivable			3,000
Goodwill			1,100
Independent dealer assets acquired in fiscal 2014 | Reacquired rights
Acquisitions
Indefinite-lived intangible asset			$ 1,100