Investments - Investment Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Investments [Abstract]
Net investment losses, before income taxes	$ (2)	$ (1,836)

Gains (losses) based on specifically identified assets and resulting from sales, investment asset write-downs, changes in the fair value of certain derivatives and equity securities and changes in allowances for credit losses on debt securities and commercial mortgage loan investments

No definition available.

Name:	ci_NetInvestmentGainLoss
Namespace Prefix:	ci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration