Investments of Insurance Subsidiaries - Schedule of Maturities of Investments (Detail) $ in Millions	Dec. 31, 2021 USD ($)
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, Amortized Cost	$ 3
Due after one year through five years, Amortized Cost	128
Due after five years through ten years, Amortized Cost	176
Due after ten years, Amortized Cost	93
Amortized Cost, Total	400
Due in one year or less, Fair Value	3
Due after one year through five years, Fair Value	135
Due after five years through ten years, Fair Value	183
Due after ten years, Fair Value	95
Fair Value, Total	$ 416

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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