Document and Entity Information - $ / shares	9 Months Ended
	Sep. 30, 2017	Oct. 20, 2017	Dec. 31, 2016
Document Document And Entity Information [Abstract]
Document Type	10-Q
Document Period End Date	Sep. 30, 2017
Entity Registrant Name	CIGNA Corporation
Entity Central Index Key	0000701221
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Trading Symbol	CI
Entity Common Stock Shares Outstanding		246,549,706
Amendment Flag	false
Entity Current Reporting Status	Yes
Entity Well Known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3
Common stock, par value per share	$ 0.25		$ 0.25