Business Segments - Market Unit Activity (Details)	3 Months Ended		9 Months Ended
	Dec. 25, 2016 USD ($)	Dec. 27, 2015 USD ($)	Dec. 25, 2016 USD ($) segment product	Dec. 27, 2015 USD ($)
Operating Segment
Number of reportable segment | segment			1
Number of product categories | product			4
Market unit activity
Revenues	$ 147,198,400	$ 139,510,700	$ 410,692,200	$ 416,528,000
Gross Profit	29,968,600	29,453,400	85,830,200	88,947,000
Public Carriers, Contractors & Program Managers
Market unit activity
Revenues	25,851,000	22,381,000	60,961,000	73,335,000
Gross Profit	4,070,000	3,678,000	10,323,000	12,485,000
Government System Operators
Market unit activity
Revenues	8,250,000	9,849,000	27,092,000	26,514,000
Gross Profit	1,843,000	2,220,000	6,075,000	6,260,000
Private System Operators
Market unit activity
Revenues	27,120,000	21,634,000	72,370,000	66,712,000
Gross Profit	6,230,000	5,093,000	16,623,000	16,293,000
Commercial Dealers & Resellers
Market unit activity
Revenues	29,913,000	32,566,000	95,599,000	100,109,000
Gross Profit	8,362,000	8,706,000	26,269,000	26,289,000
Retailer, Independent Dealer Agents & Carriers
Market unit activity
Revenues	56,064,000	53,081,000	154,670,000	149,858,000
Gross Profit	$ 9,464,000	$ 9,756,000	$ 26,540,000	$ 27,620,000