Acquisition (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended		1 Months Ended			1 Months Ended	3 Months Ended	6 Months Ended								0 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Nov. 30, 2011 FirstAssist [Member]	Nov. 30, 2011 FirstAssist [Member] Scenario, Previously Reported [Member]	Nov. 30, 2011 FirstAssist [Member] Restatement Adjustment [Member]	Jan. 31, 2012 HealthSpring [Member]	Jun. 30, 2011 HealthSpring [Member]	Jun. 30, 2012 HealthSpring [Member]	Jun. 30, 2011 HealthSpring [Member]	Jan. 31, 2012 HealthSpring [Member] Subject To Appraisal [Member]	Jan. 31, 2012 HealthSpring [Member] Vested Options [Member]	Jan. 31, 2012 HealthSpring [Member] Unvested Options [Member]	Jan. 31, 2012 HealthSpring [Member] Restricted Stock [Member]	Jan. 31, 2012 HealthSpring [Member] Customer Relationships [Member]	Jan. 31, 2012 HealthSpring [Member] Other [Member]	Jul. 12, 2012 Finansbank Joint Venture [Member]	May 10, 2012 Great American Supplemental Benefits Group [Member]
Business Acquisition, Cost of Acquired Entity, Purchase Price [Abstract]
Common Stock, Shares, Outstanding								67,800,000				922,000
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
Fair value of share-based compensation awards								65
Additional cash and equity consideration								21
Total merger consideration					115			3,811
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, low end of range								1.8
Expected option life assumption, high end of range								4.8
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					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]
Investments								612
Cash and cash equivalents								492
Premiums, accounts and notes receivable								320
Goodwill					63	56	7	2,545
Intangible Assets					40	58	(18)	795
Other								89
Total assets acquired								4,853
Insurance liabilities								508
Deferred income taxes								208
Debt								326
Total liabilities acquired								1,042
Net assets acquired								3,811
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 Emiklilik	Great American Supplemental Benefits Group
Estimated Acquisition Cost																		100	300
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.											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 joint venture will provide Cigna opportunities to reach and serve the growing middle class market in Turkey through Finansbank’s network of retail banking branches
Business Combination Goodwill Recognized Segment Allocation [Text Block]					International segment			Health Care segment
Acquisition-related costs, pre-tax										41
Acquistion-related costs, after-tax										28
Estimated fair value of intangible assets								795								711	84
Estimated Useful Life (In Years)																8 years	3-10 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	7,457	5,507	14,245	10,918						2,500
Business Acquisition Percentage Of Voting Interests Acquired																		51.00%
Business Acquisition, Date of Acquisition Agreement																		July 12, 2012	May 10, 2012
Business Acquisition, Pro Forma Information [Abstract]
Total revenues									6,887	14,734	13,699
Shareholders' net income									$ 440	$ 761	$ 867
Earnings per share:
Basic									$ 1.55	$ 2.66	$ 3.04
Diluted									$ 1.52	$ 2.62	$ 2.98