Segment Information - Segment Operating Results (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 240,325	$ 319,116	$ 862,507	$ 1,076,244
Segment EBITDA	69,294	98,278	300,208	358,746
Marketing Services
Segment Reporting Information [Line Items]
Revenue	208,504	287,794	767,553	980,072
Segment EBITDA	66,733	96,448	289,423	347,178
SaaS
Segment Reporting Information [Line Items]
Revenue	31,821	31,322	94,954	96,172
Segment EBITDA	$ 2,561	$ 1,830	$ 10,785	$ 11,568