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Derivative Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended	9 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Derivatives, Fair Value [Line Items]
Companys hedged interest rate transactions		4 years
Outstanding hedge contracts				$ 0
Deferred gains (losses) in comprehensive loss related to foreign exchange hedging		$ 0		0
Deferred (losses) gains on derivative financial instruments	$ (3,000,000)		$ (12,000,000)
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Outstanding hedge contracts		820,000,000		820,000,000
Deferred gain (loss) on derivative financial instruments		(30,000,000)
Deferred (losses) gains on derivative financial instruments				$ (8,000,000)
Unrealized pre-tax (losses) gains on derivative financial instruments			(15,000,000)
Unrealized pre-tax (losses) gains on derivative financial instruments		(29,000,000)
Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Unrealized pre-tax (losses) gains on derivative financial instruments			(1,000,000)
Foreign Exchange Contract | Other Income (Expense)
Derivatives, Fair Value [Line Items]
Realized foreign exchange forward contract gain (loss)		(2,000,000)	2,000,000
Unrealized foreign exchange forward contract gain (loss)		0	$ 2,000,000
Sale
Derivatives, Fair Value [Line Items]
Outstanding hedge contracts		121,000,000
Purchase
Derivatives, Fair Value [Line Items]
Outstanding hedge contracts		$ 61,000,000

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- Definition

Nominal or face amount used to calculate payment on derivative.

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Maximum period the entity is hedging its exposure to the variability in future cash flows for forecasted transactions, excluding those forecasted transactions related to the payment of variable interest on existing financial instruments, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

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Amount, before tax and reclassification, of gain (loss) from derivative instrument designated and qualifying cash flow hedge included in assessment of hedge effectiveness.

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Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Amount after tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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Deferred gains losses in comprehensive loss related to foreign exchange dedging.

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