Debt - Schedule of Debt (Details) - USD ($)	9 Months Ended	12 Months Ended
Debt - Schedule of Debt (Details) - USD ($)	Sep. 30, 2025	Dec. 31, 2024	Aug. 12, 2025	Jun. 30, 2025
Debt Instrument [Line Items]
Outstanding Balance	$ 12,631,000,000	$ 10,588,000,000
Fair Value	12,536,000,000	10,151,000,000
Asset Management
Debt Instrument [Line Items]
Outstanding Balance	4,775,000,000	4,279,000,000
Fair Value	4,867,000,000	4,307,000,000
Amortization of note discount	47,000,000	$ 44,000,000
Asset Management \| Senior Notes
Debt Instrument [Line Items]
Outstanding Balance	$ 0
Asset Management \| Senior Notes \| 4.40%, 2026 Senior Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	4.40%	4.40%
Outstanding Balance	$ 500,000,000	$ 499,000,000
Fair Value	$ 500,000,000	$ 496,000,000
Asset Management \| Senior Notes \| 4.87%, 2029 Senior Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	4.87%	4.87%
Outstanding Balance	$ 675,000,000	$ 675,000,000
Fair Value	$ 684,000,000	$ 670,000,000
Asset Management \| Senior Notes \| 2.65% 2030 Senior Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	2.65%	2.65%
Outstanding Balance	$ 497,000,000	$ 497,000,000
Fair Value	$ 463,000,000	$ 439,000,000
Asset Management \| Senior Notes \| 6.38% 2033 Senior Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	6.38%	6.38%
Outstanding Balance	$ 493,000,000	$ 492,000,000
Fair Value	$ 552,000,000	$ 542,000,000
Asset Management \| Senior Notes \| 5.15% 2035 Senior Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	5.15%	5.15%	5.15%
Outstanding Balance	$ 494,000,000	$ 0
Fair Value	$ 503,000,000	$ 0
Asset Management \| Senior Notes \| 5.00%, 2048 Senior Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	5.00%	5.00%
Outstanding Balance	$ 297,000,000	$ 297,000,000
Fair Value	$ 275,000,000	$ 271,000,000
Asset Management \| Senior Notes \| 6.25% 2054 Senior Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	5.80%	5.80%
Outstanding Balance	$ 741,000,000	$ 741,000,000
Fair Value	$ 761,000,000	$ 753,000,000
Asset Management \| Subordinated Notes \| 7.63% 2053 Subordinated Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	7.63%	7.63%
Outstanding Balance	$ 585,000,000	$ 584,000,000
Fair Value	$ 630,000,000	$ 642,000,000
Asset Management \| Subordinated Notes \| 6.63% 2054 Subordinated Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	6.00%	6.00%
Outstanding Balance	$ 493,000,000	$ 494,000,000
Fair Value	499,000,000	494,000,000
Retirement Services
Debt Instrument [Line Items]
Outstanding Balance	7,856,000,000	6,309,000,000
Fair Value	$ 7,669,000,000	$ 5,844,000,000
Retirement Services \| Senior Notes \| 4.13% 2028 Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	4.13%	4.13%
Outstanding Balance	$ 1,038,000,000	$ 1,050,000,000
Fair Value	$ 998,000,000	$ 976,000,000
Retirement Services \| Senior Notes \| 6.15% 2030 Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	6.15%	6.15%
Outstanding Balance	$ 568,000,000	$ 579,000,000
Fair Value	$ 533,000,000	$ 519,000,000
Retirement Services \| Senior Notes \| 3.50% 2031 Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	3.50%	3.50%
Outstanding Balance	$ 518,000,000	$ 520,000,000
Fair Value	$ 475,000,000	$ 452,000,000
Retirement Services \| Senior Notes \| 6.65% 2033 Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	6.65%	6.65%
Outstanding Balance	$ 396,000,000	$ 395,000,000
Fair Value	$ 435,000,000	$ 425,000,000
Retirement Services \| Senior Notes \| 5.88% 2034 Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	5.88%	5.88%
Outstanding Balance	$ 585,000,000	$ 584,000,000
Fair Value	$ 628,000,000	$ 608,000,000
Retirement Services \| Senior Notes \| 3.95% 2051 Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	3.95%	3.95%
Outstanding Balance	$ 544,000,000	$ 544,000,000
Fair Value	$ 364,000,000	$ 360,000,000
Retirement Services \| Senior Notes \| 3.45% 2052 Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	3.45%	3.45%
Outstanding Balance	$ 504,000,000	$ 504,000,000
Fair Value	$ 330,000,000	$ 322,000,000
Retirement Services \| Senior Notes \| 6.25% 2054 Senior Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	6.25%	6.25%
Outstanding Balance	$ 982,000,000	$ 983,000,000
Fair Value	$ 1,021,000,000	$ 1,003,000,000
Retirement Services \| Senior Notes \| 6.63% 2055 Senior Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	6.63%	6.63%		6.625%
Outstanding Balance	$ 979,000,000	$ 0
Fair Value	$ 1,071,000,000	$ 0
Retirement Services \| Subordinated Notes \| 6.63% 2054 Subordinated Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	6.63%	6.63%
Outstanding Balance	$ 592,000,000	$ 592,000,000
Fair Value	$ 608,000,000	$ 598,000,000
Retirement Services \| Subordinated Notes \| 6.88% 2055 Subordinated Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	6.88%	6.88%		6.875%
Outstanding Balance	$ 592,000,000	$ 0
Fair Value	$ 615,000,000	$ 0
Retirement Services \| Subordinated Notes \| 7.25% 2064 Subordinated Notes
Debt Instrument [Line Items]
Weighted Average Interest Rate	7.25%	7.25%
Outstanding Balance	$ 558,000,000	$ 558,000,000
Fair Value	$ 591,000,000	$ 581,000,000