Revenue from Contracts with Customers - Disaggregation of Revenue (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Total Revenues	$ 69,633	$ 150,829
Performance obligation, amount	$ 1,100	$ 1,100
Performance obligation, period	3 years	3 years
Agency & Digital Services
Disaggregation of Revenue [Line Items]
Total Revenues	$ 7,500	$ 22,612
Database Marketing Solutions
Disaggregation of Revenue [Line Items]
Total Revenues	8,904	$ 18,474
Estimated customer life		2 months
Database Marketing Solutions | Minimum
Disaggregation of Revenue [Line Items]
Estimated customer life		4 years
Database Marketing Solutions | Maximum
Disaggregation of Revenue [Line Items]
Estimated customer life		5 years
Direct Mail, Logistics, and Fulfillment
Disaggregation of Revenue [Line Items]
Total Revenues	34,956	$ 67,205
Contact Centers
Disaggregation of Revenue [Line Items]
Total Revenues	18,273	$ 42,538
Contact Centers | Minimum
Disaggregation of Revenue [Line Items]
Estimated customer life		6 months
Contact Centers | Maximum
Disaggregation of Revenue [Line Items]
Estimated customer life		1 year
Revenue for performance obligations recognized over time
Disaggregation of Revenue [Line Items]
Total Revenues	66,377	$ 143,878
Revenue for performance obligations recognized over time | Agency & Digital Services
Disaggregation of Revenue [Line Items]
Total Revenues	7,186	22,022
Revenue for performance obligations recognized over time | Database Marketing Solutions
Disaggregation of Revenue [Line Items]
Total Revenues	8,365	16,653
Revenue for performance obligations recognized over time | Direct Mail, Logistics, and Fulfillment
Disaggregation of Revenue [Line Items]
Total Revenues	32,553	62,665
Revenue for performance obligations recognized over time | Contact Centers
Disaggregation of Revenue [Line Items]
Total Revenues	18,273	42,538
Revenue for performance obligations recognized at a point in time
Disaggregation of Revenue [Line Items]
Total Revenues	3,256	6,951
Revenue for performance obligations recognized at a point in time | Agency & Digital Services
Disaggregation of Revenue [Line Items]
Total Revenues	314	590
Revenue for performance obligations recognized at a point in time | Database Marketing Solutions
Disaggregation of Revenue [Line Items]
Total Revenues	539	1,821
Revenue for performance obligations recognized at a point in time | Direct Mail, Logistics, and Fulfillment
Disaggregation of Revenue [Line Items]
Total Revenues	2,403	4,540
Revenue for performance obligations recognized at a point in time | Contact Centers
Disaggregation of Revenue [Line Items]
Total Revenues	0	0
B2B
Disaggregation of Revenue [Line Items]
Total Revenues	14,800	33,483
Consumer Brands
Disaggregation of Revenue [Line Items]
Total Revenues	15,828	35,171
Financial Services
Disaggregation of Revenue [Line Items]
Total Revenues	14,441	28,922
Healthcare
Disaggregation of Revenue [Line Items]
Total Revenues	4,083	8,461
Retail
Disaggregation of Revenue [Line Items]
Total Revenues	15,836	32,215
Transportation
Disaggregation of Revenue [Line Items]
Total Revenues	$ 4,645	$ 12,577