Investments (Components of Net Investment Gains Losses) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Marketable Securities, Gain (Loss) [Abstract]
Fixed maturity securities — net gains (losses) on sales and disposals (1)	$ 328	$ 251	$ 318
Equity securities — net gains (losses) on sales and disposals	117	19	43
Other net investment gains (losses):
FVO securities — FVO general account securities	0	0	0
Mortgage Loans	14	(231)	(93)
Real estate and real estate joint ventures	603	182	433
Other limited partnership interests	(59)	(64)	(66)
Other	(113)	(130)	1
Subtotal - investment portfolio gains (losses)	855	(155)	540
FVO CSEs - changes in estimated fair value subsequent to consolidation:
Securities	0	1	0
Long-term debt — related to securities	(1)	0	0
Non-investment portfolio gains (losses)	(1,162)	471	69
Subtotal	(1,163)	472	69
Total net investment gains (losses)	(308)	317	609
Fixed Maturity Securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(10)	(107)	(59)
Net investment gains (losses)	318	144	259
Consumer
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(63)	(2)
Industrial
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(21)	(15)
Communications
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(4)	0	(20)
Communications
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(3)	0
Corporate fixed maturity securities [Member]
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(4)	(87)	(37)
RMBS
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(18)	(16)
ABS
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(3)	(2)	0
State and political subdivision
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(3)	0	(6)
Equity securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(25)	(75)	(37)
Net investment gains (losses)	92	(56)	6
Common stock
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(24)	(75)	(36)
Non-redeemable preferred stock
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	$ (1)	$ 0	$ (1)

Consolidated securitization entities.

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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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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.

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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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Trading and other securities, fair value option, general account securities changes in estimated fair value.

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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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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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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.

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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.

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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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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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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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