Fair Value of Financial Instruments - Recurring Basis (Details) - Assets and liabilities measured at fair value - USD ($) $ in Thousands	Mar. 31, 2021	Sep. 30, 2020
Assets
Current derivative assets	$ 2,177	$ 1,398
Noncurrent derivative assets	229	222
Total assets measured at fair value	2,406	1,620
Liabilities
Current derivative liabilities	6,350	4,557
Noncurrent derivative liabilities	4,537	14,070
Total liabilities measured at fair value	20,903	29,245
Deltenna
Liabilities
Contingent consideration to seller	3,205	3,004
Shield Aviation
Liabilities
Contingent consideration to seller	6,811	5,566
H4 Global
Liabilities
Contingent consideration to seller		1,148
Delerrok Inc.
Liabilities
Contingent consideration to seller		900
Level 2
Assets
Current derivative assets	2,177	1,398
Noncurrent derivative assets	229	222
Total assets measured at fair value	2,406	1,620
Liabilities
Current derivative liabilities	6,350	4,557
Noncurrent derivative liabilities	4,537	14,070
Total liabilities measured at fair value	10,887	18,627
Level 3
Liabilities
Total liabilities measured at fair value	10,016	10,618
Level 3 \| Deltenna
Liabilities
Contingent consideration to seller	3,205	3,004
Level 3 \| Shield Aviation
Liabilities
Contingent consideration to seller	$ 6,811	5,566
Level 3 \| H4 Global
Liabilities
Contingent consideration to seller		1,148
Level 3 \| Delerrok Inc.
Liabilities
Contingent consideration to seller		$ 900

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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