Business Segments - Segment Activity (Details)	3 Months Ended	6 Months Ended
Sep. 29, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 29, 2019 USD ($) segment product	Sep. 30, 2018 USD ($)
Business Segments
Number of reportable segment \| segment			2
Number of product categories \| product			4
Market unit activity
Revenues	$ 141,810,900	$ 158,636,100	$ 272,540,200	$ 309,555,500
Gross Profit	26,319,300	31,394,700	51,582,800	62,092,800
Income (loss) before provision for (benefit from) income taxes	239,000	1,672,600	(3,290,700)	3,235,000
Segments
Market unit activity
Directly allocable expenses	10,879,000	13,106,000	23,464,000	24,996,000
Income (loss) before provision for (benefit from) income taxes	15,440,000	18,289,000	28,119,000	37,097,000
Corporate
Market unit activity
Directly allocable expenses	15,201,000	16,616,000	31,410,000	33,862,000
Public carrier
Market unit activity
Revenues	39,169,000	39,694,000	72,655,000	80,054,000
Gross Profit	4,860,000	4,780,000	9,113,000	10,406,000
Value-added resellers and integrators
Market unit activity
Revenues	64,482,000	68,650,000	129,676,000	134,197,000
Gross Profit	15,324,000	16,912,000	31,293,000	32,829,000
Retail
Market unit activity
Revenues	38,160,000	50,292,000	70,209,000	95,304,000
Gross Profit	6,135,000	9,703,000	11,177,000	18,858,000
Commercial Segment
Market unit activity
Revenues	103,651,000	108,344,000	202,331,000	214,251,000
Gross Profit	20,184,000	21,692,000	40,406,000	43,235,000
Commercial Segment \| Segments
Market unit activity
Directly allocable expenses	7,868,000	8,562,000	17,438,000	16,643,000
Income (loss) before provision for (benefit from) income taxes	12,316,000	13,130,000	22,968,000	26,592,000
Commercial Segment \| Public carrier
Market unit activity
Revenues	39,169,000	39,694,000	72,655,000	80,054,000
Gross Profit	4,860,000	4,780,000	9,113,000	10,406,000
Commercial Segment \| Value-added resellers and integrators
Market unit activity
Revenues	64,482,000	68,650,000	129,676,000	134,197,000
Gross Profit	15,324,000	16,912,000	31,293,000	32,829,000
Retail Segment
Market unit activity
Revenues	38,160,000	50,292,000	70,209,000	95,304,000
Gross Profit	6,135,000	9,703,000	11,177,000	18,858,000
Retail Segment \| Segments
Market unit activity
Directly allocable expenses	3,011,000	4,544,000	6,026,000	8,353,000
Income (loss) before provision for (benefit from) income taxes	3,124,000	5,159,000	5,151,000	10,505,000
Retail Segment \| Retail
Market unit activity
Revenues	38,160,000	50,292,000	70,209,000	95,304,000
Gross Profit	$ 6,135,000	$ 9,703,000	$ 11,177,000	$ 18,858,000

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