v3.21.1

Revenues (Contract liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Contract balances
Deferred contract revenues, recorded in other current liabilities	$ 115	$ 133
Deferred contract revenues, recorded in other long-term liabilities	304	323
Total contract liabilities	$ 419	$ 456	$ 534	$ 529

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

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