Investments - Portfolio composition (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Investments [Abstract]
Fixed income securities, at fair value	$ 39,989	$ 42,565
Equity securities, at fair value	3,807	3,168
Mortgage loans, net	752	746
Limited partnership interests	7,578	4,563
Short-term investments, at fair value	6,428	6,807
Other, net	3,286	1,691
Total	$ 61,840	$ 59,540

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), classified as current.

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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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