Acquisition (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended			1 Months Ended			1 Months Ended	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Jan. 31, 2012	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]	Mar. 31, 2012 HealthSpring [Member]	Mar. 31, 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]
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							$ 3,726
Fair value of share-based compensation awards							65
Additional cash and equity consideration							21
Total merger consideration				115			3,812
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	2,547
Intangible Assets				40	58	(18)	795
Other							94
Total assets acquired							4,860
Insurance liabilities							514
Deferred income taxes							208
Debt							326
Total liabilities acquired							1,048
Net assets acquired							3,812
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.
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.
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.
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	6,788	5,411						1,000
Business Acquisition, Pro Forma Information [Abstract]
Total revenues								7,277	6,812
Shareholders' net income								$ 381	$ 427
Earnings per share:
Basic								$ 1.33	$ 1.49
Diluted								$ 1.32	$ 1.46