Segment Information Reportable Segment Information (Reconciliation of Total Segment Operating Income to Consolidated Operating Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Total revenues	$ 332,393	$ 299,893
Gross Profit	273,262	248,880
Direct Costs By Segment	218,015	198,018
Income from operations	55,247	50,862
Fax and Martech [Member]
Segment Reporting Information [Line Items]
Total revenues	94,667	93,283
Gross Profit	82,166	78,719
Direct Costs By Segment	31,714	34,102
Income from operations	50,452	44,617
Voice, Backup, Security and CPP [Member]
Segment Reporting Information [Line Items]
Total revenues	75,117	58,962
Gross Profit	49,258	41,043
Direct Costs By Segment	43,976	27,127
Income from operations	5,282	13,916
Cloud Services Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	169,784	152,245
Gross Profit	131,424	119,762
Direct Costs By Segment	75,690	61,229
Income from operations	55,734	58,533
Digital Media Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	162,691	147,683
Gross Profit	141,920	129,153
Direct Costs By Segment	136,968	130,167
Income from operations	4,952	(1,014)
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Total revenues	(83)	(36)
Gross Profit	(83)	(36)
Direct Costs By Segment	(83)	(36)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Total revenues	332,392	299,892
Gross Profit	273,261	248,879
Direct Costs By Segment	212,575	191,360
Income from operations	60,686	57,519
Corporate [Member]
Segment Reporting Information [Line Items]
Total revenues	1	1
Gross Profit	1	1
Direct Costs By Segment	5,440	6,658
Global Operating Costs	$ 5,439	$ 6,657