Revenues (Narrative) (Details) - USD ($) $ in Billions	6 Months Ended
Jun. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Total deferred revenue	$ 3.2	$ 3.0
Deferred revenue recognized during period	1.8
Revenue not yet recognized	$ 35.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of revenue recognition	24 months
Expected timing of revenue recognition, percentage	50.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Expected timing of revenue recognition
Expected timing of revenue recognition, percentage	50.00%

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=123360276&loc=SL49130531-203044

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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-Section 50
-Paragraph 8
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

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-Publisher FASB
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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

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-Publisher FASB
-Name Accounting Standards Codification
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Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Percentage of remaining performance obligation to total remaining performance obligation not recognized as revenue.

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