Investments of Insurance Subsidiaries - Schedule of Maturities of Investments (Detail) $ in Millions	Sep. 30, 2022 USD ($)
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, Amortized Cost	$ 26
Due after one year through five years, Amortized Cost	127
Due after five years through ten years, Amortized Cost	181
Due after ten years, Amortized Cost	76
Amortized Cost, Total	410
Due in one year or less, Fair Value	26
Due after one year through five years, Fair Value	121
Due after five years through ten years, Fair Value	155
Due after ten years, Fair Value	67
Fair Value, Total	$ 369

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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