Financial Instruments - Cash Flow Hedges in AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Increase in fair value:
Interest rate agreements	$ 123,017	$ 53,241
Other comprehensive income (loss), net of tax
Interest rate agreements	4,566	3,647
Total other comprehensive income from hedging, net of tax	$ 127,583	$ 56,888	$ (22,944)

Amount, after tax and reclassification, of gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness, attributable to parent.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=124509347&loc=d3e637-108580

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