Fair Value of Financial Instruments - Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Sep. 30, 2018
Level 2
Debt instruments
Fair Value	$ 197,200	$ 193,700
Carrying value	200,000	200,000
Assets and liabilities measured at fair value
Assets
Cash equivalents		9,000
Current derivative assets	2,727	1,803
Noncurrent derivative assets	325	314
Total assets measured at fair value	3,052	11,117
Liabilities
Current derivative liabilities	1,460	1,657
Noncurrent derivative liabilities		75
Total liabilities measured at fair value	14,009	10,846
Assets and liabilities measured at fair value \| Deltenna
Liabilities
Contingent consideration to seller	1,424	1,081
Assets and liabilities measured at fair value \| Shield Aviation
Liabilities
Contingent consideration to seller	5,912	5,618
Assets and liabilities measured at fair value \| H4 Global
Liabilities
Contingent consideration to seller	313	665
Assets and liabilities measured at fair value \| Nuvotronics
Liabilities
Contingent consideration to seller	4,900
Assets and liabilities measured at fair value \| Revenue Targets \| TeraLogics
Liabilities
Contingent consideration to seller		1,750
Assets and liabilities measured at fair value \| Level 1
Assets
Cash equivalents		9,000
Total assets measured at fair value		9,000
Assets and liabilities measured at fair value \| Level 2
Assets
Current derivative assets	2,727	1,803
Noncurrent derivative assets	325	314
Total assets measured at fair value	3,052	2,117
Liabilities
Current derivative liabilities	1,460	1,657
Noncurrent derivative liabilities		75
Total liabilities measured at fair value	1,460	1,732
Assets and liabilities measured at fair value \| Level 3
Liabilities
Total liabilities measured at fair value	12,549	9,114
Assets and liabilities measured at fair value \| Level 3 \| Deltenna
Liabilities
Contingent consideration to seller	1,424	1,081
Assets and liabilities measured at fair value \| Level 3 \| Shield Aviation
Liabilities
Contingent consideration to seller	5,912	5,618
Assets and liabilities measured at fair value \| Level 3 \| H4 Global
Liabilities
Contingent consideration to seller	313	665
Assets and liabilities measured at fair value \| Level 3 \| Nuvotronics
Liabilities
Contingent consideration to seller	$ 4,900
Assets and liabilities measured at fair value \| Level 3 \| Revenue Targets \| TeraLogics
Liabilities
Contingent consideration to seller		$ 1,750

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled beyond one year or the normal operating cycle, if longer.

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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value of financial and nonfinancial obligations.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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