Investments - Gross unrealized losses by unrealized loss position and credit quality (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Investment grade fixed income securities
Investments [Line Items]
Fixed income securities with unrealized loss position less than 20% of amortized cost, net	$ (2,422,000,000)
Fixed income securities with unrealized loss position greater than or equal to 20% of amortized cost, net	(567,000,000)
Total unrealized losses	2,989,000,000	$ 196,000,000
Below investment grade fixed income securities
Investments [Line Items]
Fixed income securities with unrealized loss position less than 20% of amortized cost, net	(439,000,000)
Fixed income securities with unrealized loss position greater than or equal to 20% of amortized cost, net	(337,000,000)
Total unrealized losses	776,000,000	46,000,000
Unrealized losses having loss of less than twenty percent	(419,000,000)
Unrealized losses	0
Fixed income securities
Investments [Line Items]
Fixed income securities with unrealized loss position less than 20% of amortized cost, net	(2,861,000,000)
Fixed income securities with unrealized loss position greater than or equal to 20% of amortized cost, net	(904,000,000)
Total unrealized losses	$ 3,765,000,000	$ 242,000,000