Revenue Recognition - Contract with Customer, Asset and Liability (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Customer receivables	$ 2,224	$ 2,346
Contract assets	145	140
Contract liabilities	987	860
Accounts receivable, gross	2,400	2,500
Allowance for doubtful accounts receivable	$ 133	$ 132

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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-Publisher FASB
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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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