Investments (Assets Supporting Experience-Rated Contractholder Liabilities) (Details) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Assets Supporting Experience-Rated Contractholder Liabilities [Line Items]
Assets supporting experience-rated contractholder liabilities, at amortized cost or cost	$ 3,112	$ 2,582
Assets supporting experience-rated contractholder liabilities, at fair value	4,282	3,707
Fixed maturities
Assets Supporting Experience-Rated Contractholder Liabilities [Line Items]
Assets supporting experience-rated contractholder liabilities, at amortized cost or cost	950	819
Assets supporting experience-rated contractholder liabilities, at fair value	938	826
Equity securities
Assets Supporting Experience-Rated Contractholder Liabilities [Line Items]
Assets supporting experience-rated contractholder liabilities, at amortized cost or cost	2,162	1,763
Assets supporting experience-rated contractholder liabilities, at fair value	3,344	2,881
Corporate securities
Assets Supporting Experience-Rated Contractholder Liabilities [Line Items]
Assets supporting experience-rated contractholder liabilities, at amortized cost or cost	69	68
Assets supporting experience-rated contractholder liabilities, at fair value	67	67
Foreign government securities
Assets Supporting Experience-Rated Contractholder Liabilities [Line Items]
Assets supporting experience-rated contractholder liabilities, at amortized cost or cost	642	544
Assets supporting experience-rated contractholder liabilities, at fair value	635	539
Obligations of U.S. government authorities and agencies and obligations of U.S. states
Assets Supporting Experience-Rated Contractholder Liabilities [Line Items]
Assets supporting experience-rated contractholder liabilities, at amortized cost or cost	239	207
Assets supporting experience-rated contractholder liabilities, at fair value	$ 236	$ 220
Public Securities
Assets Supporting Experience-Rated Contractholder Liabilities [Line Items]
Assets supporting experience-rated contractholder liabilities, at amortized cost percentage	100.00%	100.00%
NAIC High or Highest Quality Rating
Assets Supporting Experience-Rated Contractholder Liabilities [Line Items]
Assets supporting experience-rated contractholder liabilities, at amortized cost percentage	99.00%	99.00%