Investments - Allowance for credit losses on fixed maturities (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Jan. 01, 2020
Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 10	$ 14	$ 12	$ 0
Impact of adoption of new accounting policy	9	14	9	14
Initial allowance for purchased securities with credit deterioration	0	0	0	0
Provision for expected credit losses on securities with no previous allowance	0	2	0	16
Additions (reductions) to previously recognized expected credit losses	0	(2)	(1)	(2)
Reductions due to sales or redemptions	(1)	0	(2)	0
Ending balance	9	14	9	14
Structured securities
Allowance for Credit Losses [Roll Forward]
Beginning balance	9	11	10	0
Impact of adoption of new accounting policy	8	11	8	11	$ 0
Initial allowance for purchased securities with credit deterioration	0	0	0	0
Provision for expected credit losses on securities with no previous allowance	0	1	0	12
Additions (reductions) to previously recognized expected credit losses	(1)	(1)	(2)	(1)
Reductions due to sales or redemptions	0	0	0	0
Ending balance	8	11	8	11
Corporate and other
Allowance for Credit Losses [Roll Forward]
Beginning balance	1	3	2	0
Impact of adoption of new accounting policy	1	3	1	3	0
Initial allowance for purchased securities with credit deterioration	0	0	0	0
Provision for expected credit losses on securities with no previous allowance	0	1	0	4
Additions (reductions) to previously recognized expected credit losses	1	(1)	1	(1)
Reductions due to sales or redemptions	(1)	0	(2)	0
Ending balance	$ 1	$ 3	$ 1	$ 3
Accounting Standards Update 2016-13
Allowance for Credit Losses [Roll Forward]
Impact of adoption of new accounting policy					$ 0