Investments (Components of Net Investment Gains Losses) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Changes In Estimated Fair Value Subsequent To Purchase For Equity Securities	$ (37)
Marketable Securities, Gain (Loss) [Abstract]
Fixed maturity securities — net gains (losses) on sales and disposals	(95)	$ (2)
Equity securities — net gains (losses) on sales and disposals	102	43
Change In Estimated Fair Value Of Equity Securities	(133)	0
Other net investment gains (losses):
Mortgage loans	(21)	(12)
Real estate and real estate joint ventures	25	(3)
Other limited partnership interests	0	(7)
Other	(130)	(26)
Subtotal	(252)	(15)
FVO CSEs - changes in estimated fair value subsequent to consolidation:
Change In Estimated Fair Value Of Other Limited Partnership Interests And Real Estate Joint Ventures	(5)	0
Non-investment portfolio gains (losses) (2)	(76)	103
Subtotal	(81)	103
Total net investment gains (losses)	(333)	88
Fixed Maturity Securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	0
Net investment gains (losses)	(95)	(2)
Equity Securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(8)
Net investment gains (losses)	(31)	35
Nonredeemable Preferred Stock [Member]
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(1)
Common Stock
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	$ 0	$ (7)

Change In Estimated Fair Value Of Equity Securities.

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Change In Estimated Fair Value Of Other Limited Partnership Interests And Real Estate Joint Ventures.

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Changes In Estimated Fair Value Subsequent To Purchase For Equity Securities Still Held As Of The End Of The Period Included In Net Income Gains (Losses).

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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.

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

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

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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