Intangible Assets and Goodwill - Details of Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 27, 2013	Apr. 28, 2012
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	$ 42,472	$ 41,249
Accumulated Amortization	26,006	24,629
Net	16,466	16,620
Indefinite-lived trade names	1,800
Customer relationships and agreements
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	16,579	14,995
Accumulated Amortization	14,213	13,720
Net	2,366	1,275
Wtd. Avg. Remaining Amortization Periods	10 years 10 months 24 days	11 years 8 months 12 days
Trade names, patents and technology licenses
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	25,774	25,774
Accumulated Amortization	11,779	10,429
Net	13,995	15,345
Wtd. Avg. Remaining Amortization Periods	10 years 4 months 24 days	11 years 9 months 18 days
Covenants not to compete
Acquired Finite-Lived Intangible Assets [Line Items]
Gross	119	480
Accumulated Amortization	14	480
Net	$ 105	$ 0
Wtd. Avg. Remaining Amortization Periods	4 years 4 months 24 days