Fair Value Measurements - Guaranteed Minimum Income Benefit Contracts (Details) (Guaranteed Minimum Income Benefit [Member], Ceded Credit Risk Secured [Member])	Mar. 31, 2015
Guaranteed Minimum Income Benefit [Member] \| Ceded Credit Risk Secured [Member]
Ceded Credit Risk [Line Items]
GMIB assets percent secured	70.00%

Percentage of GMIB assets secured by assets in trust or letters of credit.

No definition available.

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