Investments - Schedule of Investments (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Investments [Abstract]
Debt securities available for sale, current	$ 2,359
Debt securities available for sale, long-term	12,896
Available-for-sale Securities	15,255
Mortgage loans, current	145
Mortgage loans, noncurrent	1,216
Mortgage loans	1,361
Other investments, current	18
Other investments, noncurrent	1,620
Other investments, total	1,638
Total investments, current	2,522	$ 111
Total investments, noncurrent	15,732	$ 112
Total investments	$ 18,254

Mortgage Loans on Real Estate, Commercial and Consumer, Net, Current

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Mortgage Loans on Real Estate, Commercial and Consumer, Net, Noncurrent

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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 debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as noncurrent.

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

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The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

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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 investments including trading securities, available-for-sale securities, held-to-maturity securities, and short-term investments classified as other and current.

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