Gains and Losses Included in Net Income (Loss) from Assets Measured at Fair Value (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Fair value of financial instruments [Abstract]
Total realized and unrealized gains (losses) included in net income, assets	$ 7	$ 14	$ 1	$ 18
Total gains (losses) included in net income attributable to assets still held, assets	(3)	2	17	2
Net Investment Income
Fair value of financial instruments [Abstract]
Total realized and unrealized gains (losses) included in net income, assets	2	13	6	16
Total gains (losses) included in net income attributable to assets still held, assets	2	2	6	6
Net investment gains (losses)
Fair value of financial instruments [Abstract]
Total realized and unrealized gains (losses) included in net income, assets	5	1	(5)	2
Total gains (losses) included in net income attributable to assets still held, assets	$ (5)	$ 0	$ 11	$ (4)