Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended				3 Months Ended	12 Months Ended												12 Months Ended								12 Months Ended							12 Months Ended						12 Months Ended
	Dec. 31, 2011 Investment	Dec. 31, 2010 Investment	Dec. 31, 2009 Investment	Mar. 31, 2011 Republic of Tunisia	Mar. 31, 2011 Portugal and Ireland Investment	Dec. 31, 2011 Perpetual Securities	Dec. 31, 2010 Perpetual Securities	Dec. 31, 2009 Perpetual Securities	Dec. 31, 2011 Perpetual Securities Lower Limit	Dec. 31, 2011 Perpetual Securities Minimum Upper Limit	Dec. 31, 2011 Perpetual Securities Europe, excluding the United Kingdom	Dec. 31, 2011 Perpetual Securities United Kingdom	Dec. 31, 2011 Perpetual Securities Japan	Dec. 31, 2011 Perpetual Securities Other Countries	Dec. 31, 2011 Investment grade Perpetual Securities	Dec. 31, 2010 Investment grade Perpetual Securities	Dec. 31, 2011 Banks/financial Institutions	Dec. 31, 2010 Banks/financial Institutions Greece Investment	Dec. 31, 2011 Banks/financial Institutions Europe, excluding the United Kingdom	Dec. 31, 2011 Banks/financial Institutions United States	Dec. 31, 2011 Banks/financial Institutions United Kingdom	Dec. 31, 2011 Banks/financial Institutions Japan	Dec. 31, 2011 Banks/financial Institutions Other Countries	Dec. 31, 2011 Banks/financial Institutions Investment grade	Dec. 31, 2010 Banks/financial Institutions Investment grade	Dec. 31, 2011 Banks/financial Institutions Below Investment Grade Investment	Dec. 31, 2010 Sovereign and Supranational Greece	Dec. 31, 2010 Other securities Investment	Dec. 31, 2011 Public Utilities Investment grade	Dec. 31, 2010 Public Utilities Investment grade	Dec. 31, 2011 Other Corporate Investment grade	Dec. 31, 2010 Other Corporate Investment grade	Dec. 31, 2011 Variable Interest Entity, Not Consolidated A Entity	Dec. 31, 2011 Parent Company	Dec. 31, 2010 Parent Company	Dec. 31, 2009 Parent Company	Dec. 31, 2011 Parent Company Investment grade	Dec. 31, 2011 Israel Electric Corp	Dec. 31, 2011 Fair Value Option	Dec. 31, 2010 Fair Value Option	Dec. 31, 2009 Fair Value Option Upper Limit
Schedule of Investments [Line Items]
Available-for-sale fixed-maturity securities, amortized cost																																					$ 120
Available-for-sale fixed maturity securities, fair value																																		138	120		138			619
Available-for-sale fixed maturity securities, recognized gains (losses)	(1,552)	(422)	(1,212)			(572)	(27)	(826)																										(1)	0	0			12	(1)	(1)
Reclassified investments from the held-to-maturity portfolio to the available-for-sale portfolio, number of investments	13	6	12		4													3										2
Reclassified investments from the held-to-maturity portfolio to the available-for-sale portfolio, amortized cost	2,500		1,300	769	631													998									178	267										800
Reclassified investments from the held-to-maturity portfolio to the available-for-sale portfolio, aggregate unrealized gain (loss)	(334)		(548)															(599)									(66)	(165)
Realized pretax investment gains (losses) from sales and redemptions	594	38	149																								(59)
Perpetual securities, interest coupons that were fixed at issuance subsequently change to a floating short-term interest rate						floating short-term interest rate of 125 to more than 300 basis points above an appropriate market index
Maturity date						25 years
Perpetual securities, floating short-term interest rate basis point above market index									1.25%	3.00%
Geographic concentration of credit risk for issuer of investments owned											69.00%	9.00%	15.00%	7.00%					38.00%	22.00%	8.00%	9.00%	23.00%
Percentage of unrealized losses attributable to securities that were investment grade															73.00%	83.00%								80.00%	53.00%				77.00%	100.00%	73.00%	51.00%
Fair value of investments in an unrealized loss position	29,310	30,654				2,507	4,379										14,000									1,100
Total Unrealized Losses	3,536	3,363				633	563										2,200									400
Number of Issuers																										5
Percentage of unrealized losses attributable to a certain number of securities																										99.00%
Number of issuers																																	161
Percentage that the lending policy requires that the fair value of the securities and/or unrestricted cash received as collateral be of the fair value of the loaned securities	102.00%
Fair value of debt securities on deposit with regulatory authorities in the United States and Japan	$ 20