Investments (Components of Net Investment Gains Losses) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Marketable Securities, Gain (Loss) [Abstract]
Fixed maturity securities — net gains (losses) on sales and disposals	$ (40)	$ 98
Equity securities — net gains (losses) on sales and disposals	43	6
Other net investment gains (losses):
Mortgage loans	(15)	(64)
Real estate and real estate joint ventures	(1)	2
Other limited partnership interests	(17)	(27)
Other	(58)	(18)
Subtotal	(96)	(132)
FVO CSEs - changes in estimated fair value subsequent to consolidation:
Commercial mortgage loans	(1)	1
Securities	0	1
Long-term debt — related to commercial mortgage loans	1	0
Non-investment portfolio gains (losses)	104	145
Subtotal	104	147
Total net investment gains (losses)	8	15
Fixed Maturity Securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(78)
Net investment gains (losses)	(40)	20
Industrial
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(71)
Communications
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(3)
U.S. corporate and foreign corporate securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(74)
RMBS
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(4)
Equity securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(8)	(51)
Net investment gains (losses)	35	(45)
Nonredeemable Preferred Stock [Member]
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(1)	0
Common Stock
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	$ (7)	$ (51)

Consolidated securitization entities.

No definition available.

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The net gain or loss incurred on assets and liabilities held by consolidated securitizations entities and all other gains and losses.

+ References

No definition available.

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- Definition

The net gain or loss resulting from the change in fair value of commercial mortgage loans held by consolidated securitization entities not required to be reported separately in the statement of income for which the Company has elected the fair value option.

+ References

No definition available.

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The net gain or loss resulting from the sale or disposal of long-term debt relating to mortgage loans of consolidated securitization entities not required to be reported separately in the statement of income for which the Company has elected the fair option.

+ References

No definition available.

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The net gain (loss) resulting from sales and other disposals of other limited partnership interests.

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No definition available.

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The net change during the reporting period in the aggregate market value of equity or debt securities held by consolidated securitization entities that are purchased and held principally for the purpose of selling them in the near future.

+ References

No definition available.

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This item represents the subtotal of gains (losses)on the investment portfolio.

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No definition available.

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This item represents the net total realized and unrealized gain (loss) included in earnings for the period as a result of selling or holding marketable securities categorized as trading, available-for-sale, or held-to-maturity, including the unrealized holding gain (loss) of held-to-maturity securities transferred to the trading security category and the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) for available-for-sale securities transferred to trading securities during the period. Additionally, this item would include any gains (losses) realized during the period from the sale of investments accounted for under the cost method of accounting and losses recognized for other than temporary impairments (OTTI) of the subject investments.

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-Publisher FASB
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The difference between the carrying value and the sale price of debt securities, not separately or otherwise categorized as trading, available-for-sale, or held-to-maturity. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 225
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-Paragraph 1
-Subparagraph (SX 210.7-04.3(a))
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The difference between the carrying value and the sale price of equity securities, not separately or otherwise categorized as trading or available-for-sale. This element includes investments in which the entity holds a small ownership stake (generally, less than 20% of the shares outstanding) and cannot exert significant influence.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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The net realized gain (loss) on investments sold during the period, not including gains (losses) on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity, which, for cash flow reporting, is a component of proceeds from investing activities.

+ References

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Amount of gain (loss) on sale or disposal of other assets.

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The net gain (loss) resulting from a sale of loans, including adjustments to record loans classified as held-for-sale at the lower-of-cost-or-market and fair value adjustments to loan held for investment purposes.

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The net gain (loss) resulting from sales and other disposals of real estate owned for investment purposes.

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-Publisher FASB
-Name Accounting Standards Codification
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- References

No definition available.

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The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

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-Name Accounting Standards Codification
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The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

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