Acquisition (Details)	3 Months Ended		9 Months Ended		1 Months Ended			1 Months Ended	3 Months Ended	9 Months Ended													3 Months Ended		0 Months Ended
	Sep. 30, 2012 USD ($)	Sep. 30, 2011 USD ($)	Sep. 30, 2012 USD ($)	Sep. 30, 2011 USD ($)	Nov. 30, 2011 FirstAssist [Member] USD ($)	Nov. 30, 2011 FirstAssist [Member] Scenario, Previously Reported [Member] USD ($)	Nov. 30, 2011 FirstAssist [Member] Restatement Adjustment [Member] USD ($)	Jan. 31, 2012 HealthSpring [Member] USD ($)	Sep. 30, 2011 HealthSpring [Member] USD ($)	Sep. 30, 2012 HealthSpring [Member] USD ($)	Sep. 30, 2011 HealthSpring [Member] USD ($)	Sep. 30, 2012 HealthSpring [Member] Pre Tax [Member] USD ($)	Sep. 30, 2012 HealthSpring [Member] After Tax [Member] USD ($)	Jan. 31, 2012 HealthSpring [Member] Maximum [Member] Y	Jan. 31, 2012 HealthSpring [Member] Minimum [Member] Y	Jan. 31, 2012 HealthSpring [Member] Vested Options [Member] USD ($)	Jan. 31, 2012 HealthSpring [Member] Unvested Options [Member] USD ($)	Jan. 31, 2012 HealthSpring [Member] Restricted Stock [Member] USD ($)	Jan. 31, 2012 HealthSpring [Member] Customer Relationships [Member] USD ($)	Jan. 31, 2012 HealthSpring [Member] Other [Member] USD ($)	Jan. 31, 2012 HealthSpring [Member] Other [Member] Maximum [Member]	Jan. 31, 2012 HealthSpring [Member] Other [Member] Minimum [Member]	Dec. 31, 2012 Finans Emelilik [Member] Scenario, Forecast [Member] USD ($)	Dec. 31, 2012 Finans Emelilik [Member] Scenario, Forecast [Member] EUR (€)	Aug. 31, 2012 Great American Supplemental Benefits Group [Member] USD ($)
Business Acquisition, Cost of Acquired Entity, Purchase Price [Abstract]
Common Stock, Shares, Outstanding								67,800,000
Less: common shares outstanding not settled in cash								(100,000)
Common shares settled in cash								67,700,000
Price per share								$ 55
Cash consideration for outstanding shares								$ 3,725,000,000
Fair value of share-based compensation awards								65,000,000
Additional cash and equity consideration								21,000,000
Total merger consideration					115			3,811,000,000															110,000,000	85,000,000	310,000,000
Business Acquisition Fair Value Of Share Based Compensation Awards [Abstract]
Conversion Ratio HealthSpring to Cigna Stock								1.24
Share Price								$ 44.43
Expected option life assumption														4.8	1.8
Effect Of Rollover Awards For Healthspring Employees [Abstract]
Number of Awards								2,711,000								589,000	1,336,000	786,000
Average exercise/award price																$ 14.04	$ 16.21	$ 44.43
Fair value of awards								90,000,000								18,000,000	37,000,000	35,000,000
Included in purchase price								65,000,000								18,000,000	28,000,000	19,000,000
Compensation expense post-acquisition								25,000,000								0	9,000,000	16,000,000
Business Acquisition Purchase Price Allocation [Abstract]
Investments								612,000,000																	211,000,000
Cash and cash equivalents								492,000,000																	36,000,000
Premiums, accounts and notes receivable								320,000,000
Reinsurance recoverables																									448,000,000
Goodwill					64,000,000	56,000,000	8,000,000	2,545,000,000																	161,000,000
Value of business acquired (reported in Deferred policy acquisition costs in Condensed Balance Sheet)																									71,000,000
Intangible Assets					40,000,000	58,000,000	(18,000,000)	795,000,000																	95,000,000
Other assets, including other intangibles																									36,000,000
Other								91,000,000
Total assets acquired								4,855,000,000																	963,000,000
Insurance liabilities								505,000,000																	634,000,000
Accounts payable, accrued expenses and other liabilities																									22,000,000
Deferred income taxes								213,000,000
Debt								326,000,000
Total liabilities acquired								1,044,000,000																	656,000,000
Net assets acquired								3,811,000,000																	307,000,000
Acquisition Text Details [Abstract]
Business Acquisition Effective Date Of Acquisition [Text Block]					November 2011			January 31, 2012
Business Acquisition Name Of Acquired Entity [Text Block]					FirstAssist Group Holdings Limited			HealthSpring, Inc.															Finans Emeklilik ve Hayat A.S.	Finans Emeklilik ve Hayat A.S.	Great American Supplemental Benefits Group
Business Acquisition Description Of Acquired Entity [Text Block]					FirstAssist is based in the United Kingdom and provides travel and protection insurance services			HealthSpring provides Medicare Advantage coverage in 11 states and the District of Columbia, as well as a large, national stand-alone Medicare prescription drug business.															Finans Emeklilik operates in life insurance, accident insurance and pension product markets.	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
Business Combination Reason For Business Combination [Text Block]					the Company expects will enhance its individual business in the U.K. and around the world.			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.															The acquisition will provide Cigna opportunities to reach and serve the growing middle class market in Turkey through Finansbank’s network of retail banking branches.	The acquisition will provide 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. Results of this business are reported in the supplemental health, life and accident business included in the International segment.
Business Combination Goodwill Recognized Segment Allocation [Text Block]					International segment			Medicare operating segment																	International Segment
Acquisition-related costs												53,000,000	40,000,000
Estimated fair value of intangible assets								795,000,000											711,000,000	84,000,000
Estimated Useful Life of Intangible Assets (In Years)																			8 years		10 years	3 years			30 years
Percent of projected benefits reflected in weighted average useful life assumption for acquired intangible assets								90.00%
HealthSpring revenues included in Company's results	7,358,000,000	5,610,000,000	21,603,000,000	16,528,000,000						4,000,000,000
Business Acquisition Percentage Of Voting Interests Acquired																							51.00%	51.00%
Business Acquisition, Date of Acquisition Agreement																									August 31, 2012
Business Acquisition Percentage Of Voting Interests Not Acquired																							49.00%	49.00%
Acquired Goodwill Amortization Period For Federal Income Tax Purposes																									15 years
Business Acquisition, Pro Forma Information [Abstract]
Total revenues									6,940,000,000	22,092,000,000	20,639,000,000
Shareholders' net income									$ 229,000,000	$ 1,227,000,000	$ 1,096,000,000
Earnings per share:
Basic									$ 0.80	$ 4.30	$ 3.84
Diluted									$ 0.79	$ 4.23	$ 3.78