Investments - Allowance for credit losses on fixed maturities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Jan. 01, 2020
Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 12	$ 0
Impact of adoption of new accounting policy	12	14
Initial allowance for purchased securities with credit deterioration	0
Provision for expected credit losses on securities with no previous allowance	0	14
Additions (reductions) to previously recognized expected credit losses	(1)
Reductions due to sales or redemptions	(1)	0
Ending balance	10	14
Structured securities
Allowance for Credit Losses [Roll Forward]
Beginning balance	10	0
Impact of adoption of new accounting policy	9	11	$ 0
Initial allowance for purchased securities with credit deterioration	0
Provision for expected credit losses on securities with no previous allowance	0	11
Additions (reductions) to previously recognized expected credit losses	(1)
Reductions due to sales or redemptions	0	0
Ending balance	9	11
Corporate and other
Allowance for Credit Losses [Roll Forward]
Beginning balance	2	0
Impact of adoption of new accounting policy	1	3	0
Initial allowance for purchased securities with credit deterioration	0
Provision for expected credit losses on securities with no previous allowance	0	3
Additions (reductions) to previously recognized expected credit losses	0
Reductions due to sales or redemptions	(1)	0
Ending balance	$ 1	$ 3
Accounting Standards Update 2016-13
Allowance for Credit Losses [Roll Forward]
Impact of adoption of new accounting policy			$ 0