Operating Segment - Market Activity (Details)	3 Months Ended
Jun. 25, 2017 USD ($) segment product	Jun. 26, 2016 USD ($)
Operating Segment
Number of reportable segment \| segment	2
Goodwill impairment	$ 0
Number of product categories \| product	4
Market unit activity
Revenues	$ 140,010,800	$ 128,860,000
Gross Profit	29,166,800	27,106,000
Income before provision for income taxes	1,216,700	138,900
Segments
Market unit activity
Directly allocatable expenses	10,267,000	9,725,000
Income before provision for income taxes	18,900,000	17,381,000
Corporate
Market unit activity
Directly allocatable expenses	17,683,000	17,242,000
Commercial Segment
Market unit activity
Revenues	91,125,000	81,026,000
Gross Profit	19,700,000	19,006,000
Commercial Segment \| Segments
Market unit activity
Directly allocatable expenses	7,697,000	7,230,000
Income before provision for income taxes	12,003,000	11,776,000
Retail Segment
Market unit activity
Revenues	48,886,000	47,834,000
Gross Profit	9,467,000	8,100,000
Retail Segment \| Segments
Market unit activity
Directly allocatable expenses	2,570,000	2,495,000
Income before provision for income taxes	6,897,000	5,605,000
Public Carriers, Contractors & Program Managers
Market unit activity
Revenues	26,598,000	16,578,000
Gross Profit	4,128,000	3,017,000
Public Carriers, Contractors & Program Managers \| Commercial Segment
Market unit activity
Revenues	26,598,000	16,578,000
Gross Profit	4,128,000	3,017,000
Government System Operators
Market unit activity
Revenues	8,445,000	9,852,000
Gross Profit	2,004,000	2,140,000
Government System Operators \| Commercial Segment
Market unit activity
Revenues	8,445,000	9,852,000
Gross Profit	2,004,000	2,140,000
Private System Operators
Market unit activity
Revenues	21,042,000	20,305,000
Gross Profit	4,607,000	4,566,000
Private System Operators \| Commercial Segment
Market unit activity
Revenues	21,042,000	20,305,000
Gross Profit	4,607,000	4,566,000
Commercial Dealers & Resellers
Market unit activity
Revenues	35,040,000	34,291,000
Gross Profit	8,961,000	9,283,000
Commercial Dealers & Resellers \| Commercial Segment
Market unit activity
Revenues	35,040,000	34,291,000
Gross Profit	8,961,000	9,283,000
Retailer, Independent Dealer Agents & Carriers
Market unit activity
Revenues	48,886,000	47,834,000
Gross Profit	9,467,000	8,100,000
Retailer, Independent Dealer Agents & Carriers \| Retail Segment
Market unit activity
Revenues	48,886,000	47,834,000
Gross Profit	$ 9,467,000	$ 8,100,000

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The aggregate total costs related to selling a firm's product and services, as well as all other general and administrative expenses. Also includes the net amount of nonoperating interest (income) expense.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

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