Gains and Losses Included in Net Income (Loss) from Assets Measured at Fair Value (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Fair value of financial instruments [Abstract]
Total realized and unrealized gains (losses) included in net income, assets	$ 0	$ 7	$ (6)	$ 4
Total gains (losses) included in net income attributable to assets still held, assets	(3)	4	3	0
Net Investment Income
Fair value of financial instruments [Abstract]
Total realized and unrealized gains (losses) included in net income, assets	2	1	4	3
Total gains (losses) included in net income attributable to assets still held, assets	2	2	4	4
Net investment gains (losses)
Fair value of financial instruments [Abstract]
Total realized and unrealized gains (losses) included in net income, assets	(2)	6	(10)	1
Total gains (losses) included in net income attributable to assets still held, assets	$ (5)	$ 2	$ (1)	$ (4)