Business Acquisitions - Narrative (Details) - USD ($) $ in Thousands				12 Months Ended
	Jun. 04, 2021	Nov. 02, 2020	Feb. 18, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Business Acquisition [Line Items]
Goodwill acquired					$ 15,844
Goodwill				$ 339,209	342,430	$ 320,095
SRFax
Business Acquisition [Line Items]
Revenue of acquiree since acquisition date					7,300
Total consideration of transactions			$ 25,000
Accounts receivable			194
Goodwill acquired					15,800
Expected income tax deductible amount					15,800
Goodwill			$ 15,844
SEOmoz | Discontinued Operations
Business Acquisition [Line Items]
Revenue of acquiree since acquisition date				14,400
Total consideration of transactions	$ 66,500
Accounts receivable	3,901
Expected income tax deductible amount				0
Amounts due under contracts	4,200
Amounts due under contracts, expected to be uncollectible	300
Goodwill	$ 41,213			$ 41,200
Inspired eLearning | Discontinued Operations
Business Acquisition [Line Items]
Revenue of acquiree since acquisition date					1,600
Total consideration of transactions		$ 20,500
Accounts receivable					1,876
Goodwill					$ 13,174