Investments (Available-For-Sale Securities By Contractual Maturities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Debt Maturities, Amortized Cost
Amortized cost	$ 91,219	$ 86,049
Available-for-sale Securities, Debt Maturities, Fair Value
Fair Value	92,787	93,586
Fixed Maturity Securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost
Amortized cost	91,219	85,802
Available-for-sale Securities, Debt Maturities, Fair Value
Fair Value	92,787	$ 93,340
Fixed Maturity AFS Securities Excluding Structured Securities [Member] \| Fixed Maturity Securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost
Due in one year or less	3,607
Due after one year through five years	16,429
Due after five years through ten years	18,366
Due after ten years	46,264
Amortized cost	84,666
Available-for-sale Securities, Debt Maturities, Fair Value
Due in one year or less	3,636
Due after one year through five years	16,449
Due after five years through ten years	18,271
Due after ten years	47,786
Fair Value	86,142
Structured Securities [Member] \| Fixed Maturity Securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost
Amortized cost	6,553
Available-for-sale Securities, Debt Maturities, Fair Value
Fair Value	$ 6,645

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth fiscal year through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Fair value of investment in debt security, measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Amortized cost of investment in debt security measured at fair value with change recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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