Investments - Allowance for credit losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance as of January 1, 2020	$ 48	$ 14
Credit losses on securities for which credit losses were not previously recorded	6	36
Reductions for securities sold during the period	(49)	0
Increase (decrease) on securities with allowance recorded in previous period	2	(2)
Balance at December 31, 2020	7	48
Residential mortgage-backed securities
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance as of January 1, 2020	1	1
Credit losses on securities for which credit losses were not previously recorded	0	1
Reductions for securities sold during the period	0	0
Increase (decrease) on securities with allowance recorded in previous period	(1)	(1)
Balance at December 31, 2020	0	1
Foreign corporate private securities
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance as of January 1, 2020	47	11
Credit losses on securities for which credit losses were not previously recorded	0	35
Reductions for securities sold during the period	(49)	0
Increase (decrease) on securities with allowance recorded in previous period	3	1
Balance at December 31, 2020	1	47
Other asset-backed securities
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance as of January 1, 2020	0	2
Credit losses on securities for which credit losses were not previously recorded		0
Reductions for securities sold during the period		0
Increase (decrease) on securities with allowance recorded in previous period		(2)
Balance at December 31, 2020		0
Foreign corporate public securities and foreign governments
Financing Receivable, Allowance for Credit Loss [Line Items]
Balance as of January 1, 2020	0
Credit losses on securities for which credit losses were not previously recorded	6
Reductions for securities sold during the period	0
Increase (decrease) on securities with allowance recorded in previous period	0
Balance at December 31, 2020	$ 6	$ 0