Revenue - Contract balances (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2019	Dec. 31, 2018
Contract balances
Receivables, inclusive of trade and unbilled	$ 76,571	$ 59,631
Contract Assets (current and non-current)	11,351	11,278
Contract Liabilities (Deferred Revenue current and non-current)	$ 41,531	$ 44,305
Revenue, Practical Expedient, Financing Component [true/false]	true
Revenue recognized that was included in the balance sheet	$ 26,400
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 due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

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- References

No definition available.

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- 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

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- 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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- Definition

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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- 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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