Investments of Insurance Subsidiaries - Schedule of Maturities of Investments (Detail) $ in Millions	Dec. 31, 2019 USD ($)
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, Amortized Cost	$ 9
Due after one year through five years, Amortized Cost	85
Due after five years through ten years, Amortized Cost	190
Due after ten years, Amortized Cost	75
Amortized Cost, Total	359
Due in one year or less, Fair Value	9
Due after one year through five years, Fair Value	88
Due after five years through ten years, Fair Value	202
Due after ten years, Fair Value	78
Fair Value, Total	$ 377

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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