Note 13 - Segment and Related Information - Information by Industry Segment (Details) - USD ($) |
3 Months Ended | |
|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
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| Sales | $ 43,314,111 | $ 38,439,639 |
| Gross profit | 12,061,622 | 10,245,033 |
| Operating profit | 4,892,852 | 4,574,090 |
| Interest charges | 326,624 | 237,841 |
| Loss on investments in equity securities | 0 | 118,077 |
| Other expense | 351,654 | 72,263 |
| Income before Provision for Income Taxes | 4,214,574 | 4,145,909 |
| Operating Segments [Member] | ||
| Sales | 43,314,111 | 38,439,639 |
| Gross profit | 12,061,622 | 10,245,033 |
| Operating profit | 6,355,386 | 6,123,915 |
| Corporate and Reconciling Items [Member] | ||
| Operating profit | 1,462,534 | 1,549,825 |
| Commercial Air Handling [Member] | Operating Segments [Member] | ||
| Sales | 21,077,475 | 16,978,444 |
| Gross profit | 7,124,068 | 5,632,095 |
| Operating profit | 4,923,311 | 4,548,801 |
| Industrial and Transportation Products [Member] | Operating Segments [Member] | ||
| Sales | 22,236,636 | 21,461,195 |
| Gross profit | 4,937,554 | 4,612,938 |
| Operating profit | $ 1,432,075 | $ 1,575,114 |
| X | ||||||||||
- Definition Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition 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. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of interest expense classified as operating and nonoperating. Includes, but is not limited to, cost of borrowing accounted for as interest expense. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition The net result for the period of deducting operating expenses from operating revenues. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of income (expense) related to nonoperating activities, classified as other. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of unrealized gain (loss) on investment. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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