Operating Segment - Market Activity (Details)	3 Months Ended		9 Months Ended
	Dec. 24, 2017 USD ($)	Dec. 25, 2016 USD ($)	Dec. 24, 2017 USD ($) segment product	Dec. 25, 2016 USD ($)
Operating Segment
Number of reportable segment | segment			2
Goodwill impairment			$ 0
Number of product categories | product			4
Market unit activity
Revenues	$ 146,260,300	$ 147,198,400	$ 431,354,600	$ 410,692,200
Gross Profit	29,599,800	29,968,600	88,689,700	85,830,200
Income before provision for income taxes	2,072,100	2,070,800	6,381,000	4,238,600
Segments
Market unit activity
Directly allocable expenses	11,317,000	12,912,000	35,101,000	36,915,000
Income before provision for income taxes	18,283,000	17,057,000	53,589,000	48,915,000
Corporate
Market unit activity
Directly allocable expenses	16,211,000	14,986,000	47,208,000	44,676,000
Commercial Segment
Market unit activity
Revenues	91,802,000	88,097,000	280,533,000	251,044,000
Gross Profit	19,251,000	19,527,000	59,136,000	57,697,000
Commercial Segment | Segments
Market unit activity
Directly allocable expenses	7,418,000	8,256,000	23,736,000	24,501,000
Income before provision for income taxes	11,833,000	11,271,000	35,400,000	33,196,000
Retail Segment
Market unit activity
Revenues	54,458,000	59,101,000	150,822,000	159,648,000
Gross Profit	10,349,000	10,442,000	29,554,000	28,133,000
Retail Segment | Segments
Market unit activity
Directly allocable expenses	3,899,000	4,656,000	11,365,000	12,414,000
Income before provision for income taxes	6,450,000	5,786,000	18,189,000	15,719,000
Public Carrier
Market unit activity
Revenues	22,721,000	25,851,000	76,742,000	60,961,000
Gross Profit	3,178,000	4,070,000	11,083,000	10,323,000
Public Carrier | Commercial Segment
Market unit activity
Revenues	22,721,000	25,851,000	76,742,000	60,961,000
Gross Profit	3,178,000	4,070,000	11,083,000	10,323,000
Government
Market unit activity
Revenues	10,680,000	8,250,000	30,150,000	27,092,000
Gross Profit	2,256,000	1,843,000	6,672,000	6,075,000
Government | Commercial Segment
Market unit activity
Revenues	10,680,000	8,250,000	30,150,000	27,092,000
Gross Profit	2,256,000	1,843,000	6,672,000	6,075,000
Private System Operators
Market unit activity
Revenues	24,844,000	22,927,000	70,093,000	64,222,000
Gross Profit	5,305,000	4,902,000	14,966,000	14,081,000
Private System Operators | Commercial Segment
Market unit activity
Revenues	24,844,000	22,927,000	70,093,000	64,222,000
Gross Profit	5,305,000	4,902,000	14,966,000	14,081,000
Value-Added Resellers
Market unit activity
Revenues	33,557,000	31,069,000	103,548,000	98,769,000
Gross Profit	8,512,000	8,712,000	26,415,000	27,218,000
Value-Added Resellers | Commercial Segment
Market unit activity
Revenues	33,557,000	31,069,000	103,548,000	98,769,000
Gross Profit	8,512,000	8,712,000	26,415,000	27,218,000
Retail
Market unit activity
Revenues	54,458,000	59,101,000	150,822,000	159,648,000
Gross Profit	10,349,000	10,442,000	29,554,000	28,133,000
Retail | Retail Segment
Market unit activity
Revenues	54,458,000	59,101,000	150,822,000	159,648,000
Gross Profit	$ 10,349,000	$ 10,442,000	$ 29,554,000	$ 28,133,000