Revenue - Contract balances (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Contract balances
Receivables, inclusive of trade and unbilled	$ 57,537	$ 62,405
Contract Assets (current and non-current)	9,079	8,595
Contract Liabilities (Deferred Revenue current and non-current)	$ 55,147	$ 45,597
Revenue, Practical Expedient, Financing Component [true/false]	true
Contract liabilities increase due to annual renewals	$ 35,000
Minimum
Contract balances
The amount of time contract assets are transferred to receivables	3 years
Maximum
Contract balances
The amount of time contract assets are transferred to receivables	5 years

The amount of time the contract assets are transferred to receivables when the right to billion normally occurs.

No definition available.

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- Definition

Amount of increase in obligation to transfer good or service to customer for which consideration from customer has been received or is due from annual renewals.

+ References

No definition available.

+ Details

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- Definition

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

+ References

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

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before 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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

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Balance Type:	debit
Period Type:	instant

- Definition

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

+ References

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Balance Type:	credit
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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.

+ References

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+ Details

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Period Type:	duration

- Details

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- Details

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