Schedule II. Condensed Financial Information of Registrant (Parent Company) (Schedule of Condensed Financial Information of Registrant, Balance Sheets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets
Cash	$ 195	$ 156	$ 75	$ 77
Fixed maturity securities available-for-sale, at fair value (amortized cost of $1 and $2)	41,197	42,604
Short term investments	1,407	1,832
Other assets	969	773
Total assets	57,194	58,522
Liabilities
Short term debt	549	13
Long term debt	2,011	2,557
Other liabilities	3,408	3,321
Total liabilities	44,543	46,208
Stockholders' Equity
Common stock ($2.50 par value; 500,000,000 shares authorized; 273,040,243 shares issued; 269,717,583 and 269,399,390 shares outstanding)	683	683
Additional paid-in capital	2,145	2,146
Retained earnings	9,495	8,774
Accumulated other comprehensive income (loss)	442	831
Treasury stock (3,322,660 and 3,640,853 shares), at cost	(91)	(99)
Notes receivable for the issuance of common stock	(23)	(21)
Total stockholders’ equity	12,651	12,314
Total liabilities and stockholders' equity	57,194	58,522
Balance Sheet Parenthetical
Common stock, par value	$ 2.50	$ 2.50
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	273,040,243	273,040,243
Common stock, shares outstanding	269,717,583	269,399,390
Treasury stock, shares	3,322,660	3,640,853
Parent Company [Member]
Assets
Investment in subsidiaries	14,708	14,427
Cash	1
Fixed maturity securities available-for-sale, at fair value (amortized cost of $1 and $2)	1	2
Short term investments	505	448
Amounts due from subsidiaries	3	2
Other assets	3	5
Total assets	15,221	14,884
Liabilities
Short term debt	549	3
Long term debt	1,981	2,527
Other liabilities	40	40
Total liabilities	2,570	2,570
Stockholders' Equity
Common stock ($2.50 par value; 500,000,000 shares authorized; 273,040,243 shares issued; 269,717,583 and 269,399,390 shares outstanding)	683	683
Additional paid-in capital	2,145	2,146
Retained earnings	9,495	8,774
Accumulated other comprehensive income (loss)	442	831
Treasury stock (3,322,660 and 3,640,853 shares), at cost	(91)	(99)
Notes receivable for the issuance of common stock	(23)	(21)
Total stockholders’ equity	12,651	12,314
Total liabilities and stockholders' equity	15,221	14,884
Balance Sheet Parenthetical
Marketable securities fixed maturities available-for-sale at amortized cost basis	$ 1	$ 2
Common stock, par value	$ 2.50	$ 2.50
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	273,040,243	273,040,243
Common stock, shares outstanding		269,399,390
Treasury stock, shares		3,640,853