Separate Account Assets and Liabilities - Separate account assets (Details) - Life and Retirement - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Fair Value, Separate Account Investment [Line Items]
Value of investment options	$ 91,005	$ 84,853
Individual Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	47,893	45,178
Group Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	38,188	34,361
Life Insurance
Fair Value, Separate Account Investment [Line Items]
Value of investment options	932	799
Institutional Markets
Fair Value, Separate Account Investment [Line Items]
Value of investment options	3,992	4,515
Equity Funds | Equity Funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	55,538	48,866
Equity Funds | Equity Funds | Individual Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	25,451	22,990
Equity Funds | Equity Funds | Group Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	28,675	24,608
Equity Funds | Equity Funds | Life Insurance
Fair Value, Separate Account Investment [Line Items]
Value of investment options	819	687
Equity Funds | Equity Funds | Institutional Markets
Fair Value, Separate Account Investment [Line Items]
Value of investment options	593	581
Bond Funds | Bond Funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	8,676	9,250
Bond Funds | Bond Funds | Individual Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	4,037	3,802
Bond Funds | Bond Funds | Group Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	3,292	4,081
Bond Funds | Bond Funds | Life Insurance
Fair Value, Separate Account Investment [Line Items]
Value of investment options	44	46
Bond Funds | Bond Funds | Institutional Markets
Fair Value, Separate Account Investment [Line Items]
Value of investment options	1,303	1,321
Balanced Funds | Balanced Funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	25,166	24,764
Balanced Funds | Balanced Funds | Individual Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	17,711	17,663
Balanced Funds | Balanced Funds | Group Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	5,479	5,113
Balanced Funds | Balanced Funds | Life Insurance
Fair Value, Separate Account Investment [Line Items]
Value of investment options	53	49
Balanced Funds | Balanced Funds | Institutional Markets
Fair Value, Separate Account Investment [Line Items]
Value of investment options	1,923	1,939
Money Market Funds | Money Market Funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	1,625	1,973
Money Market Funds | Money Market Funds | Individual Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	694	723
Money Market Funds | Money Market Funds | Group Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	742	559
Money Market Funds | Money Market Funds | Life Insurance
Fair Value, Separate Account Investment [Line Items]
Value of investment options	16	17
Money Market Funds | Money Market Funds | Institutional Markets
Fair Value, Separate Account Investment [Line Items]
Value of investment options	$ 173	$ 674