Investments (Net Investment Income) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Net investment income	$ 11,893us-gaap_NetInvestmentIncome	$ 11,785us-gaap_NetInvestmentIncome	$ 11,852us-gaap_NetInvestmentIncome
Less: Investment expenses	838	844	743
Variable Interest Entity, Primary Beneficiary, Consolidated Securitization Entities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Net investment income	1	3	4
Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	8,260	8,279	8,295
Equity securities
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	86	78	68
Actively Traded Securities At Estimated Fair Value And Fvo General Account Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	23	43	77
Mortgage loans
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	2,378	2,405	2,528
Policy loans
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	448	440	451
Real estate and real estate joint ventures
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	725	699	593
Other limited partnership interests
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	721	633	555
Cash, cash equivalents and short-term investments
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	26	32	19
Operating joint ventures
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	2	(4)	(2)
Other Investments [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Gross Investment Income, Operating	61	21	7
Securities Investment [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Net investment income	11,892	11,782	11,848
Gross Investment Income, Operating	12,730	12,626	12,591
Available-for-sale Securities [Member] \| Variable Interest Entity, Primary Beneficiary, Consolidated Securitization Entities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Net investment income	$ 1	$ 3	$ 4

Amount, before investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 2

-Article 7

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.9)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 16

-Article 12

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 3: http://www.xbrl.org/2003/role/presentationRef

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