Shareholders' Equity and Dividend Availability (details) (USD $)	3 Months Ended				12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Jun. 07, 2011
Shareholders' Equity and Dividend Availability disclosure
Common stock, shares authorized	1,750,000,000				1,750,000,000	1,748,600,000
Number of authorized shares, voting common stock	1,745,000,000				1,745,000,000
Number of authorized shares, undesignated shares	5,000,000				5,000,000
Share repurchase authorization, number of shares repurchased (in shares)	20,900,000	7,300,000	3,900,000	18,900,000	51,000,000
Share repurchase authorization, cost of shares repurchased	$ 1,188,000,000	$ 375,000,000	$ 237,000,000	$ 1,100,000,000	$ 2,900,000,000
Share repurchase authorization, average price paid per share	$ 56.74	$ 51.77	$ 60.27	$ 58.23	$ 56.86
Share repurchase authorization, remaining capacity under share repurchase authorization	3,609,000,000	4,797,000,000	5,172,000,000	5,409,000,000	3,609,000,000
Shares acquired to cover tax withholding costs and exercise costs					82,000,000	66,000,000
Number of common shares issued upon conversion of preferred shares, per preferred share	8				8
Preferred shares outstanding	0				0	200,000		190,083
Number of common shares issued upon conversion of preferred shares, total								1,520,000
Maximum amount of dividends available to be paid by subsidiaries to their parent without prior approval of the Connecticut Insurance Department	1,960,000,000				1,960,000,000
Dividends received by holding company from its domestic insurance subsidiaries	2,330,000,000				2,330,000,000
Statutory net income of the Company's domestic and international insurance subsidiaries					1,500,000,000	3,690,000,000	3,900,000,000
Policyholder surplus of the Company's domestic and international insurance subsidiaries	$ 19,170,000,000				$ 19,170,000,000	$ 20,070,000,000