Investments - Investments by Category (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Current
Investments per Consolidated Balance Sheets	$ 914	$ 905	[1]
Long-term
Investments per Consolidated Balance Sheets	19,010	16,288	[1]
Total
Investments per Consolidated Balance Sheets	19,924	17,193
Debt securities
Current
Investments per Consolidated Balance Sheets	616	654
Long-term
Investments per Consolidated Balance Sheets	9,293	9,218
Total
Investments per Consolidated Balance Sheets	9,909	9,872
Equity securities
Current
Investments per Consolidated Balance Sheets	51	45
Long-term
Investments per Consolidated Balance Sheets	3,069	577
Total
Investments per Consolidated Balance Sheets	3,120	622
Commercial mortgage loans
Current
Investments per Consolidated Balance Sheets	106	67
Long-term
Investments per Consolidated Balance Sheets	1,501	1,547
Total
Investments per Consolidated Balance Sheets	1,607	1,614
Policy loans
Current
Investments per Consolidated Balance Sheets	0	0
Long-term
Investments per Consolidated Balance Sheets	1,211	1,218
Total
Investments per Consolidated Balance Sheets	1,211	1,218
Other long-term investments
Current
Investments per Consolidated Balance Sheets	0	0
Long-term
Investments per Consolidated Balance Sheets	3,936	3,728
Total
Investments per Consolidated Balance Sheets	3,936	3,728
Short-term investments
Current
Investments per Consolidated Balance Sheets	141	139
Long-term
Investments per Consolidated Balance Sheets	0	0
Total
Investments per Consolidated Balance Sheets	$ 141	$ 139

[1] Amounts have been restated to reflect the adoption of Targeted Improvements to the Accounting for Long-Duration Contracts in 2023. See Note 2 to the Consolidated Financial Statements for further information.