Revenue Recognition - Customer Receivables and Contract Balances (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Capitalized Contract Cost [Line Items]
Customer receivables	$ 618	$ 683
Contract assets	32	38
Contract liabilities	259	385
Accounts receivable, gross	657	728
Allowance for credit losses	39	$ 45
Disposal Group, Held-for-sale, Not Discontinued Operations
Capitalized Contract Cost [Line Items]
Customer receivables	82
Contract assets	0
Contract liabilities	$ 62

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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