Fair Value Measurements - Level 2 Financial Assets and Financial Liabilities (Details)	Sep. 30, 2014
Fair Value Disclosures [Abstract]
Percentage of investments in fixed maturities and equity securities classified as Level 2	92.00%
Maximum percentage of investments classified in Level 2 representing foreign bonds priced using unadjusted broker quotes	1.00%

Maximum percentage of Level 2 investments representing foreign bonds priced using a single unadjusted market-observable input derived by averaging multiple broker-dealer quotes.

No definition available.

Name:	ci_MaximumPercentLevel2InvestmentsForeignBondsBrokerQuote
Namespace Prefix:	ci_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant