Revenue Recognition - Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Customer receivables	$ 1,830	$ 1,889
Contract assets	85	108
Contract liabilities	876	950
Accounts receivable, gross	2,000	2,100
Allowance for doubtful accounts receivable	$ 137	$ 174

Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.

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Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business.

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Amount of allowance for credit loss on accounts receivable.

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Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

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