Fair Value Measurements - Information about Valuation Inputs for Variable Interest Entity Assets and Liabilities Classified as Level 3 (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Estimated Future Premium Payments Weighted Average Discounted Rate	3.20%	3.00%
Asset-backed Securities [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Inputs Coupon Rate	5.97%	5.98%
Fair Value Inputs Maturity	12 years 9 months 18 days	13 years 5 months 15 days
Fair Value Inputs Yield	12.00%	12.60%
Variable Interest Entity [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held			$ 235
Estimated Future Premium Payments Weighted Average Discounted Rate	6.30%	6.80%
Estimated Future Premium Payments Minimum Discounted Rate	5.30%	5.80%
Estimated Future Premium Payments Maximum Discounted Rate	7.80%	8.50%