Condensed Financial Information of Parent Company - Balance Sheets (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets
Short Term Investments	$ 1,318	$ 2,114
Taxable Fixed Maturities (cost $1,213 and $1,095)	38,780	37,091
Equity Securities (cost $- and $-)	1,964	1,810
TOTAL INVESTED ASSETS	43,485	42,613
Other Assets	1,138	1,205
TOTAL ASSETS	51,286	50,433	52,184
Liabilities
Long Term Debt	3,300	3,300
Dividend Payable to Shareholders	117	110
Accrued Expenses and Other Liabilities	2,299	1,357
TOTAL LIABILITIES	34,990	34,336
Shareholders' Equity
Preferred Stock - Authorized 8,000,000 Shares; $1 Par Value; Issued - None
Common Stock - Authorized 1,200,000,000 Shares; $1 Par Value; Issued 371,980,460 Shares	372	372
Paid-In Surplus	171	171
Retained Earnings	23,520	21,902
Accumulated Other Comprehensive Income	1,110	1,035
Treasury Stock, at Cost - 139,551,071 and 123,673,969 Shares	(8,877)	(7,383)
TOTAL SHAREHOLDERS' EQUITY	16,296	16,097	15,827
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	51,286	50,433
Parent Company [Member]
Assets
Short Term Investments	574	856
Taxable Fixed Maturities (cost $1,213 and $1,095)	1,226	1,110
Equity Securities (cost $- and $-)		2
TOTAL INVESTED ASSETS	1,800	1,968
Investment in Consolidated Subsidiaries	17,838	17,455
Other Assets	168	165
TOTAL ASSETS	19,806	19,588
Liabilities
Long Term Debt	3,300	3,300
Dividend Payable to Shareholders	117	110
Accrued Expenses and Other Liabilities	93	81
TOTAL LIABILITIES	3,510	3,491
Shareholders' Equity
Preferred Stock - Authorized 8,000,000 Shares; $1 Par Value; Issued - None
Common Stock - Authorized 1,200,000,000 Shares; $1 Par Value; Issued 371,980,460 Shares	372	372
Paid-In Surplus	171	171
Retained Earnings	23,520	21,902
Accumulated Other Comprehensive Income	1,110	1,035
Treasury Stock, at Cost - 139,551,071 and 123,673,969 Shares	(8,877)	(7,383)
TOTAL SHAREHOLDERS' EQUITY	16,296	16,097
TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY	$ 19,806	$ 19,588