Fair Value Measurements - Gains or losses recorded related to fair value option (Details) - Fair Value Option - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Fair Value, Option, Quantitative Disclosures
Fair value option gain (loss)	$ 212	$ 182
Other bond securities
Fair Value, Option, Quantitative Disclosures
Fair value option gain (loss)	136	(319)
Alternative investments
Fair Value, Option, Quantitative Disclosures
Fair value option gain (loss)	77	398
Long-term debt
Fair Value, Option, Quantitative Disclosures
Fair value option gain (loss)	$ (1)	$ 103