Acquisitions and Dispositions - Additional Disclosures (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended								12 Months Ended			0 Months Ended	12 Months Ended			0 Months Ended	12 Months Ended							12 Months Ended		1 Months Ended					1 Months Ended		1 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Nov. 09, 2012 Finans Emeklilik [Member]	Dec. 31, 2013 Finans Emeklilik [Member]	Dec. 31, 2012 Finans Emeklilik [Member]	Dec. 31, 2011 Finans Emeklilik [Member]	Aug. 31, 2012 Great American Supplemental Benefits Group [Member]	Dec. 31, 2013 Great American Supplemental Benefits Group [Member]	Dec. 31, 2012 Great American Supplemental Benefits Group [Member]	Dec. 31, 2011 Great American Supplemental Benefits Group [Member]	Dec. 31, 2013 HealthSpring [Member]	Dec. 31, 2012 HealthSpring [Member]	Dec. 31, 2011 HealthSpring [Member]	Jan. 31, 2012 HealthSpring [Member] States	Dec. 31, 2012 HealthSpring [Member] Pre Tax [Member]	Dec. 31, 2012 HealthSpring [Member] After Tax [Member]	Jan. 31, 2012 HealthSpring [Member] Maximum [Member]	Jan. 31, 2012 HealthSpring [Member] Minimum [Member]	Jan. 31, 2012 HealthSpring [Member] Vested Options [Member]	Jan. 31, 2012 HealthSpring [Member] Unvested Options [Member]	Jan. 31, 2012 HealthSpring [Member] Restricted Stock Grants And Units [Member]	Jan. 31, 2012 HealthSpring [Member] Customer Relationships [Member]	Jan. 31, 2012 HealthSpring [Member] Other Intangibles [Member]	Jan. 31, 2012 HealthSpring [Member] Other Intangibles [Member] Maximum [Member]	Jan. 31, 2012 HealthSpring [Member] Other Intangibles [Member] Minimum [Member]
Business Acquisition, Entity Acquired and Reason for Acquisition [Abstract]
Business Acquisition Effective Date Of Acquisition													Nov. 09, 2012				Aug. 31, 2012			Jan. 31, 2012
Business Acquisition Name Of Acquired Entity													Finans Emeklilik ve Hayat A.S.				Great American Supplemental Benefits Group			HealthSpring, Inc.
Business Acquisition Percentage Of Voting Interests Acquired												51.00%
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners												49.00%
Business Acquisition Description Of Acquired Entity													Finans Emeklilik operates in life insurance, accident insurance and pension product markets.				one of the largest providers of supplemental health insurance products in the U.S.			HealthSpring provides Medicare Advantage coverage in 15 states and the District of Columbia, as well as a large, national stand-alone Medicare prescription drug business.
Business Combination Reason For Business Combination													The acquisition provides Cigna opportunities to reach and serve the growing middle class market in Turkey through Finansbank’s network of retail banking branches.				The acquisition provides the Company with an increased presence in the Medicare supplemental benefits market. It also extends the Company’s global direct-to-consumer retail channel as well as further enhances its distribution network of agents and brokers.			The acquisition of HealthSpring strengthens the Company’s ability to serve individuals across their life stages as well as deepens its presence in a number of geographic markets. The addition of HealthSpring brings industry leading physician partnership capabilities and creates the opportunity to deepen the Company’s existing client and customer relationships, as well as facilitates a broader deployment of its range of health and wellness capabilities and product offerings.
Healthspring Medicare Advantage Coverage Number Of States																							15
Minority Interest Redemption Term												15 years
Business Acquisition, Cost of Acquired Entity, Purchase Price [Abstract]
HealthSpring, Inc. common shares outstanding at January 30, 2012	275,526				285,829				275,526	285,829	285,533												67,828
Less: common shares outstanding not settled in cash																							(100)
Common shares settled in cash																							67,728
Price per share																							$ 55
Cash consideration for outstanding shares																							$ 3,725
Fair value of share-based compensation awards																							65
Additional cash and equity consideration																							21
Total merger consideration												116											3,811
Business Acquisition Fair Value Of Share Based Compensation Awards [Abstract]
Conversion Ratio Health Spring To Cigna Stock																							1.24
Share Price																							$ 44.43
Expected option life assumption																										4 years 9 months 18 days	1 year 9 months 18 days
Effect Of Rollover Awards For Healthspring Employees [Abstract]
Number of Awards																							2,711					589	1,336	786
Average exercise/award price																												$ 14.04	$ 16.21	$ 44.43
Fair value of awards																							90					18	37	35
Included in purchase price																							65					18	28	19
Compensation expense post-acquisition																							25					0	9	16
Business Acquisition Purchase Price Allocation [Abstract]
Business Acquisition Purchase Price Allocation Methodology																				In accordance with GAAP, the total purchase price has been allocated to the tangible and intangible net assets acquired based on management's estimates of their fair values.
Allocation to the value of business acquired asset												26				144
Allocation to insurance liabilities												58				707							505
Allocation to goodwill												116				168							2,541
Business Combination Goodwill Recognized Segment Allocation													Global Supplemental Benefits segment				Global Supplemental Benefits Segment			Government operating segment
Business Acquisition Purchase Price Allocation Goodwill Expected Tax Deductible Amount Description																	Substantially all of the goodwill is tax deductible and will be amortized over the next 15 years for federal income tax purposes.
Acquired Goodwill Amortization Period For Federal Income Tax Purposes																15 years
Intangible assets												113				168							795								711	84
Acquired Finite-lived Intangible Asset, Weighted Average Useful Life												10 years				15 years															8 years		10 years	3 years
Revenues included in the Company's results	8,151	8,066	7,980	8,183	7,620	7,323	7,422	6,754	32,380	29,119	21,865										5,400
Business Combination, Acquisition Related Costs																								53	40
Percent of intangible asset value to be amortized within one year																				50.00%
Business Acquisition Pro Forma Information [Abstract]
Total Revenues																					29,608	27,461
Shareholders' net income																					$ 1,633	$ 1,456
Earnings Per Share [Abstract]
Basic																					$ 5.73	$ 5.11
Diluted																					$ 5.63	$ 5.02
Pro forma information																				Pro forma information. The following table presents selected unaudited pro forma information for the Company assuming the acquisition of HealthSpring had occurred as of January 1, 2011. This pro forma information does not purport to represent what the Company’s actual results would have been if the acquisition had occurred as of the date indicated or what such results would be for any future periods.