Investments - Change in unrealized net capital gains and losses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Change in Unrealized Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss)
Change in unrealized net capital gains and losses	$ 872
Amounts recognized for:
Other unrealized net capital gains and losses, pre-tax	(5)
Deferred income taxes	(185)
Increase in unrealized net capital gains and losses, after-tax	682	$ (1,594)
Limited partnership interests
Change in Unrealized Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss)
Change in unrealized net capital gains and losses	2
Fixed income securities
Change in Unrealized Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss)
Change in unrealized net capital gains and losses	868
Short-term investments
Change in Unrealized Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss)
Change in unrealized net capital gains and losses	1
Derivative instruments
Change in Unrealized Gain (Loss) Recognized in Accumulated Other Comprehensive Income (Loss)
Change in unrealized net capital gains and losses	$ 1