INVESTMENTS - Components of Net Investment Income (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									$ 3,520	$ 3,309	$ 3,033
Less investment expenses									47	29	26
Net investment income	876	869	845	882	858	843	784	794	3,473	3,280	3,007
Fixed Maturities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									3,248	3,026	2,695
Perpetual securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									253	274	328
Equity securities
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									17	5	4
Short Term Investments and Cash Equivalents
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income									$ 2	$ 4	$ 6