Amount of amortization expense for asset recognized from cost incurred to obtain or fulfill contract with customer.

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Amortization period of cost capitalized in obtaining or fulfilling contract with customer, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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- Definition

Indicates (true false) whether practical expedient was elected not to adjust consideration for effect of financing component when transfer and customer payment for product or service occurs within one year or less.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Indicates (true false) whether practical expedient was elected to recognize incremental cost of obtaining contract as expense when incurred if amortization period would have been one year or less.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Indicates (true false) whether optional exemption was applied not to disclose amount of transaction price allocated to and explanation of expected timing of revenue recognition for remaining performance obligation, when contract has expected duration of one year or less or right to consideration corresponds directly to performance completed.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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

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Remaining duration of performance obligation for which optional exemption was applied not to disclose amount of transaction price allocated to and timing of revenue recognition for remaining performance obligation, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Revenue Narratives (Details) - USD ($) $ in Millions	12 Months Ended
Revenue Narratives (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Contract with Customer, Liability, Revenue Recognized	$ 36.2	$ 41.1
Capitalized Contract Cost, Amortization	$ 1.6	$ 1.5	$ 1.3
Revenue, Practical Expedient, Incremental Cost of Obtaining Contract [true false]	true
Revenue, Practical Expedient, Financing Component [true false]	true
Revenue, Remaining Performance Obligation, Optional Exemption, Performance Obligation [true false]	true
Maximum [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Capitalized Contract Cost, Amortization Period	1 year
Revenue, Remaining Performance Obligation, Optional Exemption, Remaining Duration	1 year
Support and Maintenance Contracts [Member] \| Maximum [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenue, Remaining Performance Obligation, Optional Exemption, Remaining Duration	1 year
Comcast CableOS Software License Agreement [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenue, Remaining Performance Obligation, Amount	$ 77.6
Significant Financing Component Revenue with Customer [Member] \| Maximum [Member]
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Revenue, Remaining Performance Obligation, Optional Exemption, Remaining Duration	1 year