Shareholders' Equity - Regulatory Requirements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Statutory Accounting Practices [Line Items]
Estimated minimum statutory surplus required by regulators	$ 9,011
Investments on deposit with regulatory bodies	684
Estimated maximum dividend distributions permitted in 2024 without prior regulatory approval	3,098
Insurance and HMO
Statutory Accounting Practices [Line Items]
Statutory net income	2,757	$ 2,851	$ 3,302
Estimated statutory capital and surplus	16,961	$ 15,503	$ 14,879
Dividends paid	$ 1,900