Business Acquisitions (Pro Forma Financial Information) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Fiscal 2022 Acquisitions
Business Acquisition [Line Items]
Revenues	$ 342,173	$ 366,258	$ 1,010,600	$ 1,041,436
Net income (loss) from continuing operations	$ 18,120	$ 4,925	$ (3,801)	$ 23,369
(Loss) income per common share from continuing operations - Basic (usd per share)	$ 0.39	$ 0.11	$ (0.08)	$ 0.52
(Loss) income per common share from continuing operations - Diluted (usd per share)	$ 0.39	$ 0.10	$ (0.08)	$ 0.49
Fiscal 2021 Acquisitions
Business Acquisition [Line Items]
Revenues		$ 374,202		$ 1,045,184
Net income (loss) from continuing operations		$ 6,886		$ 25,490
(Loss) income per common share from continuing operations - Basic (usd per share)		$ 0.15		$ 0.56
(Loss) income per common share from continuing operations - Diluted (usd per share)		$ 0.14		$ 0.54
SEOmoz Acquisition
Business Acquisition [Line Items]
Revenues		$ 367,414		$ 1,028,545
Net income (loss) from continuing operations		$ 6,610		$ 24,030
(Loss) income per common share from continuing operations - Basic (usd per share)		$ 0.14		$ 0.53
(Loss) income per common share from continuing operations - Diluted (usd per share)		$ 0.14		$ 0.51