Fair Value Measurements (excluding Consolidated Investment Entities) - Fair Value Measurement (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Assets held in separate accounts | $ 93,133 | $ 80,174 |
Total assets | 157,085 | 146,606 |
Derivatives | 371 | 389 |
Total liabilities | 151,032 | 141,609 |
Fixed maturities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 28,611 | 30,357 |
U.S. Treasuries | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 403 | 581 |
U.S. Government agencies and authorities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 56 | 59 |
State, municipalities, and political subdivisions | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 771 | 845 |
U.S. corporate public securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 7,666 | 8,201 |
U.S. corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 4,760 | 4,692 |
Foreign corporate public securities and foreign governments | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,702 | 2,949 |
Foreign corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,812 | 3,034 |
Residential mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 3,476 | 3,977 |
Commercial mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 3,495 | 3,883 |
Other asset-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,470 | 2,136 |
Assets measured on recurring basis | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 28,611 | 30,357 |
Cash and cash equivalents, short-term investments and short-term investments under securities loan agreements | 2,165 | 2,454 |
Assets held in separate accounts | 93,133 | 80,174 |
Total assets | 124,517 | 113,838 |
Contingent consideration liability | 51 | 112 |
Total liabilities | 480 | 553 |
Assets measured on recurring basis | Stabilizer and MCGs | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Investment contract liabilities | 9 | 6 |
Assets measured on recurring basis | Credit Default Swap | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 2 | 2 |
Assets measured on recurring basis | Interest rate contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 270 | 341 |
Derivatives | 354 | 376 |
Assets measured on recurring basis | Foreign exchange contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 37 | 80 |
Derivatives | 13 | 10 |
Assets measured on recurring basis | Equity contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 4 | 1 |
Derivatives | 2 | 1 |
Assets measured on recurring basis | Embedded derivatives on reinsurance . | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 61 | 95 |
Embedded derivative on reinsurance liability | 49 | 46 |
Assets measured on recurring basis | U.S. Treasuries | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 403 | 581 |
Assets measured on recurring basis | U.S. Government agencies and authorities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 56 | 59 |
Assets measured on recurring basis | State, municipalities, and political subdivisions | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 771 | 845 |
Assets measured on recurring basis | U.S. corporate public securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 7,666 | 8,201 |
Assets measured on recurring basis | U.S. corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 4,760 | 4,692 |
Assets measured on recurring basis | Foreign corporate public securities and foreign governments | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,702 | 2,949 |
Assets measured on recurring basis | Foreign corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,812 | 3,034 |
Assets measured on recurring basis | Residential mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 3,476 | 3,977 |
Assets measured on recurring basis | Commercial mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 3,495 | 3,883 |
Assets measured on recurring basis | Other asset-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,470 | 2,136 |
Assets measured on recurring basis | Equity securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Equity securities | 236 | 336 |
Assets measured on recurring basis | Level 1 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 346 | 433 |
Cash and cash equivalents, short-term investments and short-term investments under securities loan agreements | 2,148 | 2,430 |
Assets held in separate accounts | 87,180 | 74,600 |
Total assets | 89,821 | 77,605 |
Contingent consideration liability | 0 | 0 |
Total liabilities | 0 | 3 |
Assets measured on recurring basis | Level 1 | Stabilizer and MCGs | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Investment contract liabilities | 0 | 0 |
Assets measured on recurring basis | Level 1 | Credit Default Swap | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 0 | 0 |
Assets measured on recurring basis | Level 1 | Interest rate contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 7 | 2 |
Derivatives | 0 | 3 |
Assets measured on recurring basis | Level 1 | Foreign exchange contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 0 | 0 |
Derivatives | 0 | 0 |
Assets measured on recurring basis | Level 1 | Equity contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 0 | 0 |
Derivatives | 0 | 0 |
Assets measured on recurring basis | Level 1 | Embedded derivatives on reinsurance . | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 0 | |
Embedded derivative on reinsurance liability | 0 | 0 |
Assets measured on recurring basis | Level 1 | U.S. Treasuries | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 346 | 433 |
Assets measured on recurring basis | Level 1 | U.S. Government agencies and authorities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 1 | State, municipalities, and political subdivisions | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 1 | U.S. corporate public securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 1 | U.S. corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 1 | Foreign corporate public securities and foreign governments | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 1 | Foreign corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 1 | Residential mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 1 | Commercial mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 1 | Other asset-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 1 | Equity securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Equity securities | 140 | 140 |
Assets measured on recurring basis | Level 2 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 26,175 | 27,575 |
Cash and cash equivalents, short-term investments and short-term investments under securities loan agreements | 17 | 24 |
Assets held in separate accounts | 5,605 | 5,227 |
Total assets | 32,162 | 33,341 |
Contingent consideration liability | 0 | 0 |
Total liabilities | 362 | 374 |
Assets measured on recurring basis | Level 2 | Stabilizer and MCGs | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Investment contract liabilities | 0 | 0 |
Assets measured on recurring basis | Level 2 | Credit Default Swap | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 2 | 2 |
Assets measured on recurring basis | Level 2 | Interest rate contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 263 | 339 |
Derivatives | 354 | 373 |
Assets measured on recurring basis | Level 2 | Foreign exchange contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 37 | 80 |
Derivatives | 13 | 10 |
Assets measured on recurring basis | Level 2 | Equity contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 4 | 1 |
Derivatives | 2 | 1 |
Assets measured on recurring basis | Level 2 | Embedded derivatives on reinsurance . | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 61 | 95 |
Embedded derivative on reinsurance liability | (9) | (12) |
Assets measured on recurring basis | Level 2 | U.S. Treasuries | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 57 | 148 |
Assets measured on recurring basis | Level 2 | U.S. Government agencies and authorities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 55 | 58 |
Assets measured on recurring basis | Level 2 | State, municipalities, and political subdivisions | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 771 | 845 |
Assets measured on recurring basis | Level 2 | U.S. corporate public securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 7,648 | 8,181 |
Assets measured on recurring basis | Level 2 | U.S. corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 3,234 | 2,891 |
Assets measured on recurring basis | Level 2 | Foreign corporate public securities and foreign governments | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,702 | 2,946 |
Assets measured on recurring basis | Level 2 | Foreign corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,376 | 2,602 |
Assets measured on recurring basis | Level 2 | Residential mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 3,419 | 3,949 |
Assets measured on recurring basis | Level 2 | Commercial mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 3,495 | 3,883 |
Assets measured on recurring basis | Level 2 | Other asset-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,418 | 2,072 |
Assets measured on recurring basis | Level 2 | Equity securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Equity securities | 0 | 0 |
Assets measured on recurring basis | Level 3 | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 2,090 | 2,349 |
Cash and cash equivalents, short-term investments and short-term investments under securities loan agreements | 0 | 0 |
Assets held in separate accounts | 348 | 347 |
Total assets | 2,534 | 2,892 |
Contingent consideration liability | 51 | 112 |
Total liabilities | 118 | 176 |
Assets measured on recurring basis | Level 3 | Stabilizer and MCGs | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Investment contract liabilities | 9 | 6 |
Assets measured on recurring basis | Level 3 | Credit Default Swap | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 0 | 0 |
Assets measured on recurring basis | Level 3 | Interest rate contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 0 | 0 |
Derivatives | 0 | 0 |
Assets measured on recurring basis | Level 3 | Foreign exchange contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 0 | 0 |
Derivatives | 0 | 0 |
Assets measured on recurring basis | Level 3 | Equity contracts | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 0 | 0 |
Derivatives | 0 | 0 |
Assets measured on recurring basis | Level 3 | Embedded derivatives on reinsurance . | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivatives | 0 | 0 |
Embedded derivative on reinsurance liability | 58 | 58 |
Assets measured on recurring basis | Level 3 | U.S. Treasuries | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 3 | U.S. Government agencies and authorities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 1 | 1 |
Assets measured on recurring basis | Level 3 | State, municipalities, and political subdivisions | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 3 | U.S. corporate public securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 18 | 20 |
Assets measured on recurring basis | Level 3 | U.S. corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 1,526 | 1,801 |
Assets measured on recurring basis | Level 3 | Foreign corporate public securities and foreign governments | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 3 |
Assets measured on recurring basis | Level 3 | Foreign corporate private securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 436 | 432 |
Assets measured on recurring basis | Level 3 | Residential mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 57 | 28 |
Assets measured on recurring basis | Level 3 | Commercial mortgage-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 0 | 0 |
Assets measured on recurring basis | Level 3 | Other asset-backed securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Fixed maturities, including securities pledged | 52 | 64 |
Assets measured on recurring basis | Level 3 | Equity securities | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Equity securities | $ 96 | $ 196 |