Business Segments - Market Unit Activity (Details)	3 Months Ended		6 Months Ended
	Sep. 25, 2016 USD ($)	Sep. 27, 2015 USD ($)	Sep. 25, 2016 USD ($) segment product	Sep. 27, 2015 USD ($)
Operating Segment
Number of reportable segment | segment			1
Number of product categories | product			4
Market unit activity
Revenues	$ 134,633,800	$ 142,353,300	$ 263,493,800	$ 277,017,300
Gross Profit	28,755,600	30,511,700	55,861,600	59,493,600
Public Carriers, Contractors & Program Managers
Market unit activity
Revenues	18,532,000	25,803,000	35,110,000	50,954,000
Gross Profit	3,236,000	4,393,000	6,253,000	8,807,000
Government System Operators
Market unit activity
Revenues	8,990,000	8,782,000	18,842,000	16,665,000
Gross Profit	2,092,000	2,093,000	4,232,000	4,040,000
Private System Operators
Market unit activity
Revenues	23,735,000	23,056,000	45,250,000	45,078,000
Gross Profit	5,429,000	5,541,000	10,393,000	11,200,000
Commercial Dealers & Resellers
Market unit activity
Revenues	32,256,000	34,055,000	65,686,000	67,543,000
Gross Profit	8,924,000	8,812,000	17,907,000	17,583,000
Retailer, Independent Dealer Agents & Carriers
Market unit activity
Revenues	51,121,000	50,657,000	98,606,000	96,777,000
Gross Profit	$ 9,075,000	$ 9,673,000	$ 17,077,000	$ 17,864,000