Consolidated Balance Sheets (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Investments [Abstract]
Fixed maturities, at fair value (amortized cost, $14,531; $15,481)	$ 16,600	$ 17,705
Equity securities, at fair value (cost, $137; $121)	131	111
Commercial Mortgage Loans	2,811	2,851
Policy loans	1,504	1,501
Real estate	82	83
Other long-term investments	1,249	1,255
Short-term investments	122	154
Total investments	22,499	23,660
Cash and cash equivalents	3,306	2,978
Accrued investment income	277	258
Premiums, accounts and notes receivable, net	1,943	1,777
Reinsurance recoverables	7,514	6,256
Deferred policy acquisition costs	1,221	1,198
Property and equipment	1,109	1,120
Deferred income taxes, net	284	374
Goodwill	5,990	6,001
Other assets, including other intangibles	2,846	2,355
Separate account assets	7,950	7,757
Total assets	54,939	53,734
Liabilities
Contractholder deposit funds	8,512	8,508
Future policy benefits	9,538	9,265
Unpaid claims and claim expenses	4,218	4,062
Health Care medical claims payable	2,000	1,856
Unearned premiums and fees	577	549
Total insurance and contractholder liabilities	24,845	24,240
Accounts payable, accrued expenses and other liabilities	6,976	6,667
Short-term debt	400	201
Long-term debt	4,995	4,986
Separate account liabilities	7,950	7,757
Total liabilities	45,166	43,851
Redeemable noncontrolling interest	113	114
Shareholders' Equity
Common stock (par value per share, $0.25; shares issued,366; authorized, 600)	92	92
Additional paid-in capital	3,305	3,295
Net unrealized appreciation, fixed maturities	811	883
Net unrealized appreciation, equity securities	6	4
Net unrealized depreciation, derivatives	(25)	(28)
Net translation of foreign currencies	11	69
Postretirement benefits liability adjustment	(1,559)	(1,599)
Accumulated other comprehensive loss	(756)	(671)
Retained earnings	12,328	12,330
Less treasury stock, at cost	(5,309)	(5,277)
Total shareholders' equity	9,660	9,769
Total liabilities and equity	$ 54,939	$ 53,734
Shareholders' Equity Per Share	$ 33.79	$ 34.18