Separate Account Assets and Liabilities - Separate account assets (Details) - USD ($) $ in Millions	Jun. 30, 2023	Jun. 30, 2022
Fair Value, Separate Account Investment [Line Items]
Value of investment options	$ 89,718	$ 86,735
Equity Funds | Equity Funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	54,100	49,488
Bond Funds | Bond funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	8,747	9,301
Balanced Funds | Balanced funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	25,217	26,358
Money Market Funds | Money market funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	1,654	1,588
Individual Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	47,409	46,262
Individual Retirement | Equity Funds | Equity Funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	24,804	23,012
Individual Retirement | Bond Funds | Bond funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	3,974	3,887
Individual Retirement | Balanced Funds | Balanced funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	17,911	18,684
Individual Retirement | Money Market Funds | Money market funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	720	679
Group Retirement
Fair Value, Separate Account Investment [Line Items]
Value of investment options	37,245	34,902
Group Retirement | Equity Funds | Equity Funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	27,889	25,210
Group Retirement | Bond Funds | Bond funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	3,428	4,010
Group Retirement | Balanced Funds | Balanced funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	5,375	5,181
Group Retirement | Money Market Funds | Money market funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	553	501
Life Insurance
Fair Value, Separate Account Investment [Line Items]
Value of investment options	888	807
Life Insurance | Equity Funds | Equity Funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	777	690
Life Insurance | Bond Funds | Bond funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	43	46
Life Insurance | Balanced Funds | Balanced funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	51	49
Life Insurance | Money Market Funds | Money market funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	17	22
Institutional Markets
Fair Value, Separate Account Investment [Line Items]
Value of investment options	4,176	4,764
Institutional Markets | Equity Funds | Equity Funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	630	576
Institutional Markets | Bond Funds | Bond funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	1,302	1,358
Institutional Markets | Balanced Funds | Balanced funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	1,880	2,444
Institutional Markets | Money Market Funds | Money market funds
Fair Value, Separate Account Investment [Line Items]
Value of investment options	$ 364	$ 386