Investments - Gross unrealized losses by unrealized loss position and credit quality (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021
Investment grade
Investment [Line Items]
Fixed income securities with unrealized loss position less than 20% of amortized cost, net	$ (2,058,000,000)
Fixed income securities with unrealized loss position greater than or equal to 20% of amortized cost, net	(360,000,000)
Total unrealized losses	(2,418,000,000)	$ (196,000,000)
Below investment grade
Investment [Line Items]
Fixed income securities with unrealized loss position less than 20% of amortized cost, net	(388,000,000)
Fixed income securities with unrealized loss position greater than or equal to 20% of amortized cost, net	(171,000,000)
Total unrealized losses	(559,000,000)	(46,000,000)
Unrealized losses having loss of less than twenty percent	(302,000,000)
Unrealized losses having loss of greater than twenty percent	0
Fixed income securities
Investment [Line Items]
Fixed income securities with unrealized loss position less than 20% of amortized cost, net	(2,446,000,000)
Fixed income securities with unrealized loss position greater than or equal to 20% of amortized cost, net	(531,000,000)
Total unrealized losses	$ (2,977,000,000)	$ (242,000,000)