Restructuring Charges - Reconciliation of Beginning and Ending Liability Balances by Major Restructuring Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Restructuring Cost And Reserve [Line Items]
Balance at December 31, 2015	$ 2,276
Restructuring charges	992	$ 216
Cash payments	(1,314)
Adjustment to liability	242
Balance at March 31, 2016	2,196
Marketing Events Group Consolidation | Employee Severance
Restructuring Cost And Reserve [Line Items]
Balance at December 31, 2015	751
Restructuring charges	499
Cash payments	(775)
Balance at March 31, 2016	475
Marketing Events Group Consolidation | Facility Closing
Restructuring Cost And Reserve [Line Items]
Balance at December 31, 2015	1,291
Restructuring charges	9
Cash payments	(165)
Balance at March 31, 2016	1,135
Other Restructuring | Employee Severance
Restructuring Cost And Reserve [Line Items]
Balance at December 31, 2015	234
Restructuring charges	484
Cash payments	(374)
Adjustment to liability	242
Balance at March 31, 2016	$ 586