Revenues - Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Disaggregation of Revenue [Line Items]
Total revenues	$ 287,889	$ 273,174	$ 568,512	$ 527,843
Transferred at Point in Time [Member]
Disaggregation of Revenue [Line Items]
Total revenues	866	4,265	1,941	8,884
Transferred over Time [Member]
Disaggregation of Revenue [Line Items]
Total revenues	287,023	268,909	566,571	518,959
Digital Media Segment [Member]
Disaggregation of Revenue [Line Items]
Total revenues	137,591	128,474	268,752	241,605
Digital Media Segment [Member] | Advertising [Member]
Disaggregation of Revenue [Line Items]
Total revenues	106,251	107,240	207,824	199,694
Digital Media Segment [Member] | Subscription [Member]
Disaggregation of Revenue [Line Items]
Total revenues	31,340	15,242	60,928	30,074
Digital Media Segment [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues	0	5,992	0	11,837
Business Cloud Services Segment [Member]
Disaggregation of Revenue [Line Items]
Total revenues	150,297	144,709	299,781	286,254
Business Cloud Services Segment [Member] | Subscription [Member]
Disaggregation of Revenue [Line Items]
Total revenues	150,127	143,418	299,448	283,751
Business Cloud Services Segment [Member] | Other [Member]
Disaggregation of Revenue [Line Items]
Total revenues	170	1,291	333	2,503
Corporate [Member]
Disaggregation of Revenue [Line Items]
Total revenues	1	0	3	0
Intersegment Elimination [Member]
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ (9)	$ (24)	$ (16)