Revenue - Contract Balances (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Trade and client receivables, net of allowance	$ 39,853	$ 30,156
Deferred revenue	15,892	13,799
Deferred revenue (component of other liabilities, noncurrent)	4,074	3,153
Calculated under Revenue Guidance in Effect before Topic 606
Disaggregation of Revenue [Line Items]
Trade and client receivables, net of allowance	$ 39,853	$ 30,156

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=121593590&loc=d3e4428-111522

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3))
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Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 45
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Name:	us-gaap_AccountsReceivableNetCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant