Acquisitions - Schedule of Consideration and Net Assets Acquired (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Goodwill	$ 542,239	$ 480,065
Customer relationships
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Acquired finite-lived intangible assets, weighted average useful life	7 years
Software and technology
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Acquired finite-lived intangible assets, weighted average useful life	3 years
Non-compete agreements
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Acquired finite-lived intangible assets, weighted average useful life	5 years
Trademarks \| Minimum
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Acquired finite-lived intangible assets, weighted average useful life	9 years
Trademarks \| Maximum
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Acquired finite-lived intangible assets, weighted average useful life	5 years
Series of Individually Immaterial Business Acquisitions
Business Combination, Separately Recognized Transactions [Line Items]
Cash paid at closing	$ 70,984	36,577
Contingent consideration from acquisitions	1,902	4,498
Deferred payment obligations to (from) sellers	(141)	0
Total consideration	72,745	41,075
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Cash	2,064	2,523
Prepaid and other current assets	5,671	1,782
Operating lease right-of-use assets	1,668	0
Property and equipment	172	411
Other assets	36	84
Total identifiable assets acquired excluding goodwill	23,922	15,338
Accruals and other current liabilities	(2,458)	(3,538)
Deferred revenues	(4,274)	(2,897)
Operating lease liabilities	(1,668)	0
Deferred income taxes	(1,005)	(1,869)
Other liabilities	(87)	0
Total liabilities assumed	(9,492)	(8,304)
Net identifiable assets acquired excluding goodwill	14,430	7,034
Goodwill	58,315	34,041
Net assets acquired	72,745	41,075
Series of Individually Immaterial Business Acquisitions \| Customer relationships
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Finite-lived intangibles	8,854	6,534
Series of Individually Immaterial Business Acquisitions \| Software and technology
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Finite-lived intangibles	2,207	2,423
Series of Individually Immaterial Business Acquisitions \| Non-compete agreements
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Finite-lived intangibles	200	150
Series of Individually Immaterial Business Acquisitions \| Trademarks
Business Combination, Recognized Identifiable Assets Acquired, Goodwill, and Liabilities Assumed, Net [Abstract]
Finite-lived intangibles	$ 3,050	$ 1,431

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Business Combination, Contingent Consideration, Liability, Initial Value

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Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Noncurrent Assets, Operating Lease, Right-Of-Use Asset

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Business Combination, Recognized Identifiable Assets Acquired And Liabilities Assumed, Noncurrent Liabilities, Operating Lease, Liability, Noncurrent

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Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

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Amount of assets acquired at the acquisition date.

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Amount of currency on hand as well as demand deposits with banks or financial institutions, acquired at the acquisition date. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Amount of asset related to consideration paid in advance for costs that provide economic benefits in future periods, and amount of other assets that are expected to be realized or consumed within one year or the normal operating cycle, if longer, acquired at the acquisition date.

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Amount of deferred revenue expected to be recognized as such within one year or the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of other liabilities due within one year or within the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of deferred tax liability attributable to taxable temporary differences assumed at the acquisition date.

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The amount of identifiable intangible assets recognized as of the acquisition date.

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Amount of liabilities assumed at the acquisition date.

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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

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Amount of other liabilities due after one year or the normal operating cycle, if longer, assumed at the acquisition date.

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Amount of other assets expected to be realized or consumed after one year or the normal operating cycle, if longer, acquired at the acquisition date.

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The amount of property, plant, and equipment recognized as of the acquisition date.

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Amount recognized for assets, including goodwill, in excess of (less than) the aggregate liabilities assumed.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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