Cover Page - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2020	Jan. 31, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-38769
Entity Registrant Name	Cigna Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-4991898
Entity Address, Address Line One	900 Cottage Grove Road
Entity Address, City or Town	Bloomfield
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06002
City Area Code	860
Local Phone Number	226-6000
Title of 12(b) Security	Common Stock, Par Value $0.01
Trading Symbol	CI
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Entity Shell Company	false
Entity Public Float			$ 68.9
Entity Common Stock, Shares Outstanding		351,845,606
Documents Incorporated by Reference	Part III of this Form 10-K incorporates by reference information from the registrant’s definitive proxy statement related to the 2021 annual meeting of shareholders.
Amendment Flag	false
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Entity Central Index Key	0001739940