Revenue Recognition - Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Customer receivables	$ 2,112	$ 2,194
Contract assets	109	130
Contract liabilities	927	1,028
Accounts receivable, gross	2,200	2,300
Allowance for doubtful accounts receivable	$ 110	$ 94

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
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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.

+ References

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Amount of allowance for credit loss on accounts receivable.

+ References

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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.

+ References

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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.

+ References

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