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Stock-based Compensation (Schedule of Stock Option Exercises) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Stock Option Aggregate Disclosures [Abstract]
Intrinsic value of stock options exercised	$ 17	$ 26	$ 65	$ 164
Cash received from option exercises	18	26	51	98
Treasury shares repurchased for employee payroll taxes	(4)	(7)	(12)	(29)
Tax benefit realized from option exercises	3	6	14	40
Aggregate grant-date fair value of stock options vested			$ 14	$ 15

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Amount of tax benefit from exercise of option under share-based payment arrangement.

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-Section 50
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Amount of cash inflow from exercise of option under share-based payment arrangement.

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