Investments - Portfolio composition (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Investments [Abstract]
Fixed income securities, at fair value	$ 66,354	$ 59,044
Equity securities, at fair value	4,710	8,162
Mortgage loans, net	4,075	4,817
Limited partnership interests	7,609	8,078
Short-term investments, at fair value	7,800	4,256
Other, net	3,689	4,005
Total investments	$ 94,237	$ 88,362

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Sum of the carrying amounts as of the balance sheet date of all investments.

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Amount of investment in equity method investee and investment in and advance to affiliate.

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The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

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Amount of investments classified as other.

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Amount of short-term investments classified as other.

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