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The amount of indemnification assets (amounts to be reimbursed if and when certain assumed liabilities are paid) recognized at the acquisition date of a business combination.

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Business acquisitions - Enquero, Inc. - Narrative (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Payment for business acquisitions, net of cash acquired		$ 72,025	$ 186,633	$ 252,276
Goodwill	$ 1,695,688	1,731,027	1,695,688	1,574,466
Acquisition related cost		$ 1,177	2,650	$ 8,352
Enquero Inc.
Business Acquisition [Line Items]
Purchase consideration	148,797
Payment for business acquisitions, net of cash acquired	137,166
Cash and cash equivalents	11,631
Cash consideration to acquired certain assets and assumed certain liabilities	$ 141,938
Acquired intangible assets, weighted average amortization period	4 years
Goodwill	$ 87,874		87,874
Acquisition related cost	1,590
Acquired assets	32,879		32,879
Liabilities assumed	17,232		17,232
Recognized net deferred tax liability	14,343		14,343
Indemnification assets	5,968		5,968
Enquero Inc. \| BCMI
Business Acquisition [Line Items]
Goodwill	2,594		2,594
Enquero Inc. \| CGRLH
Business Acquisition [Line Items]
Goodwill	22,548		22,548
Enquero Inc. \| HMS
Business Acquisition [Line Items]
Goodwill	62,732		62,732
Enquero Inc. \| Customer-related intangible assets
Business Acquisition [Line Items]
Acquired intangibles	49,000		49,000
Enquero Inc. \| Marketing-related intangible assets
Business Acquisition [Line Items]
Acquired intangibles	9,500		9,500
Enquero Inc. \| Technology-related intangible assets
Business Acquisition [Line Items]
Acquired intangibles	$ 1,400		$ 1,400
Hoodoo Digital, LLC
Business Acquisition [Line Items]
Ownership percentage acquired (in percentage)		100.00%
Purchase consideration		$ 66,592
Payment for business acquisitions, net of cash acquired		64,310
Cash and cash equivalents		2,283
Cash consideration to acquired certain assets and assumed certain liabilities		$ 67,695
Acquired intangible assets, weighted average amortization period		5 years
Goodwill		$ 44,216
Acquisition related cost		1,177
Acquired assets		5,629
Liabilities assumed		1,852
Indemnification assets		278
Hoodoo Digital, LLC \| BCMI
Business Acquisition [Line Items]
Goodwill		4,167
Hoodoo Digital, LLC \| CGRLH
Business Acquisition [Line Items]
Goodwill		7,032
Hoodoo Digital, LLC \| HMS
Business Acquisition [Line Items]
Goodwill		33,017
Hoodoo Digital, LLC \| Customer-related intangible assets
Business Acquisition [Line Items]
Acquired intangibles		16,200
Hoodoo Digital, LLC \| Marketing-related intangible assets
Business Acquisition [Line Items]
Acquired intangibles		$ 2,400