Segment Information (Geographical Revenue Information) (Details) (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
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues	$ 7,735	$ 6,442	[1]	$ 4,574	$ 7,661	$ 5,638	$ 4,520	$ 5,401	$ 6,300	$ 26,412	$ 21,859	$ 22,049
United States of America [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues										21,814	21,561	22,140
Japan [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues										4,363	135	(329)
Other [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Revenues										$ 235	$ 163	$ 238

[1] On March 1, 2013, the Company filed Amendment No. 1 on Form 10-Q/A to amend and restate its Quarterly Report on Form 10-Q for the three and nine months ended September 30, 2012 as originally filed with the Securities and Exchange Commission on November 1, 2012. In this restatement the Company recognized an estimated pre-tax reinsurance loss on disposition of $533 comprised of impairment of goodwill attributed to the Individual Life business of $342 and a loss accrual for premium deficiency of $191 in the third quarter of 2012. The estimate is subject to change pending final determination of net assets sold, transaction costs, and other adjustments. The effect of the restatement is summarized as follows: Three months ended September 30, 2012 As previouslyreportedAdjustmentAs restatedIncome (loss) from continuing operations, net of tax$403$(388)$15Net income (loss)$401$(388)$13Net income (loss) available to common shareholders$391$(388)$3Basic earnings (losses) per common share$0.90$(0.89)$0.01Diluted earnings (losses) per common share$0.83$(0.82)$0.01