Anticipated period for billing and collecting incurred cost associated with specific contract.

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- Definition

Common stock dividend rate percentage.

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- Definition

Represents the percentage cost basis reduction for inventories related to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. Inventories are valued at the lower of cost or market, with cost being determined principally by using the last-in, first-out (LIFO) method and market defined as replacement cost for raw materials and net realizable value for work in process and finished goods. Appropriate consideration is given to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. The cost of work in process and finished goods includes materials, direct labor, variable costs and overhead. The Company evaluates the need to record inventory adjustments on all inventories, including raw material, work in process, finished goods, spare parts and used equipment. Used equipment acquired by the Company on trade-in from customers is carried at estimated net realizable value.

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- Definition

Inventory cost basis determination period maximum.

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- Definition

Inventory cost basis determination period minimum.

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No definition available.

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- Definition

Represents the inventory valuation estimate amount after accounting for inventories related to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. Inventories are valued at the lower of cost or market, with cost being determined principally by using the last-in, first-out (LIFO) method and market defined as replacement cost for raw materials and net realizable value for work in process and finished goods. Appropriate consideration is given to obsolescence, excessive levels, deterioration, possible alternative uses and other factors in determining net realizable value. The cost of work in process and finished goods includes materials, direct labor, variable costs and overhead. The Company evaluates the need to record inventory adjustments on all inventories, including raw material, work in process, finished goods, spare parts and used equipment. Used equipment acquired by the Company on trade-in from customers is carried at estimated net realizable value.

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No definition available.

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- Definition

Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]

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No definition available.

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- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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- Definition

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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- Definition

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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- Definition

The sum of the realized and unrealized net gain (loss) on trading securities during the period.

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- Definition

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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No definition available.

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- Definition

Number of options vested.

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No definition available.

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- Definition

Description of the stock split arrangement. Also provide the retroactive effect given by a stock split that occurs after the balance date but before the release of financial statements.

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Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

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Nature of Operations and Summary of Significant Accounting Policies - Additional Information (Detail)		12 Months Ended
	Jul. 11, 2016	Sep. 30, 2017 USD ($) Segment shares	Sep. 30, 2016 USD ($) shares	Sep. 30, 2015 USD ($) shares
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Stock split ratio		1.5
Exercisable stock options, included in the diluted EPS calculation \| shares		463,000	480,000	0
Effect of dilutive stock options \| shares		284,000	190,000	0
Anti-dilutive exercisable stock options, not included in the diluted EPS calculation \| shares		0	0	512,000
Net unrealized gains (losses)		$ 1,183,000	$ 2,502,000	$ (4,882,000)
Transfers of investments between Level 1 and Level 2		0	0
Impairment loss recognized on an asset group		$ 0	0	$ 0
Time for the collection of cost associated with Pre- contract		1 year
Valuation allowance		$ 0	$ 0
Number of reportable segment \| Segment		1
Common and Class B Stock [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Stock split ratio	1.5
Stock dividend percentage	50.00%
Stock split ratio description		On July 11, 2016, the Company's Board of Directors approved a three-for-two split of the Company's common and Class B stock to be effected in the form of a 50% stock dividend. As a result, shareholders received one additional share of common or Class B stock for every two shares they held of the respective class of stock as of the record date.
Entities Owned by One Global Company [Member] \| Revenue [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration		13.00%	14.00%	15.00%
Entities Owned by One Global Company [Member] \| Revenue [Member] \| Customer One [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration		10.00%
Entities Owned by One Global Company [Member] \| Revenue [Member] \| Maximum [Member] \| Customer One [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Percentage of concentration			1.00%	1.00%
Three to Four Years Old Inventory [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Cost basis reduction in inventory, percentage		50.00%
Inventory, minimum time period on the shelf, years		3 years
Inventory, maximum time period on the shelf, years		4 years
Four to Five Years Old Inventory [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Cost basis reduction in inventory, percentage		75.00%
Inventory, minimum time period on the shelf, years		4 years
Inventory, maximum time period on the shelf, years		5 years
Greater Than Five Years Old Inventory [Member]
Nature Of Operations And Summary Of Significant Accounting Policies [Line Items]
Inventory, minimum time period on the shelf, years		5 years
Inventory valuation estimate		$ 0