Document and Entity Information - $ / shares	9 Months Ended
	Sep. 30, 2019	Oct. 15, 2019	Dec. 31, 2018
Document Document And Entity Information [Abstract]
Document Type	10-Q
Document Fiscal Period Focus	Q3
Document Fiscal Year Focus	2019
Document Period End Date	Sep. 30, 2019
Current Fiscal Year End Date	--12-31
Document Quarterly Report	true
Document Transition Report	false
Amendment Flag	false
Entity File Number	1-08323
Registrant Name	Cigna Corporation
Entity Incorporation State Country Code	DE
Entity Tax Identification Number	82-4991898
Central Index Key	0001739940
Entity Address	900 Cottage Grove Road
Entity Address City	Bloomfield
Entity Address State	CT
Entity Address Postal	06002
City Area	860
Local Phone	226-6000
Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Filer Category	Large Accelerated Filer
Smaller reporting company	false
Emerging growth company	false
Shell company	false
Title of 12(b) Security	Common Stock, Par Value $0.01
Common stock, par value per share	$ 0.01		$ 0.01
Trading Symbol	CI
Common Stock outstanding		373,425,371
Security exchange name	NYSE