Income Taxes (Details 3) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance, January 1	$ 726	$ 701	$ 821
Increases:
Current year tax positions	57	66	152
Tax positions related to prior years	105	78	47
Effects of foreign currency translations	0	10	0
Decreases:
Tax positions related to prior years	(24)	(14)	(74)
Settlements with tax authorities	(15)	(40)	(192)
Lapse of statute of limitations	(58)	(75)	(44)
Effects of foreign currency translations	(1)	0	(9)
Balance, December 31	$ 790	$ 726	$ 701

Decrease in unrecognized tax benefits excluding amounts pertaining to examined tax returns.

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Increase in unrecognized tax benefits excluding amounts pertaining to examined tax returns.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount of unrecognized tax benefits.

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Amount of decrease in unrecognized tax benefits resulting from foreign currency translation.

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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from foreign currency translation.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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