Segment Information Reportable Segment Information (Reconciliation of Total Segment Operating Income to Consolidated Operating Income) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 280,623	$ 254,669
Direct Costs By Segment	227,176	201,877
Income from operations	46,158	47,975
Global Operating Costs	7,312	4,823
Depreciation, Depletion and Amortization, Nonproduction	42,618	39,322
Business Cloud Services Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	149,485	141,544
Direct Costs By Segment	92,594	85,244
Income from operations	56,891	56,300
Depreciation, Depletion and Amortization, Nonproduction	14,378	16,764
Digital Media Segment [Member]
Segment Reporting Information [Line Items]
Total revenues	131,161	113,131
Direct Costs By Segment	134,582	116,633
Income from operations	(3,421)	(3,502)
Depreciation, Depletion and Amortization, Nonproduction	27,114	22,558
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Total revenues	(24)	(6)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Income from operations	53,470	52,798
Depreciation, Depletion and Amortization, Nonproduction	$ 41,492	$ 39,322