Accounts Receivable and Allowance for Expected Credit Losses - Writeoff (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Allowance for Doubtful Accounts and Unbilled Services [Abstract]
Provision for expected credit losses	$ 6,580	$ 3,984	$ 14,816	$ 15,608
Write-offs	$ 5,746	$ 6,182	$ 15,464	$ 19,707

Allowance for Doubtful Accounts and Unbilled Services [Abstract]

No definition available.

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- Definition

Amount of direct write-downs of accounts receivable charged against the allowance.

+ References

+ Details

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- Definition

Amount of expense (reversal of expense) for expected credit loss on accounts receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=124255953&loc=SL82919249-210447

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(5))
-URI http://asc.fasb.org/extlink&oid=123367319&loc=SL114868664-224227

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