Restructuring Charges - Reconciliation of Beginning and Ending Liability Balances by Major Restructuring Activity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reconciliation of beginning and ending liability balances by major restructuring activity
Beginning Balance				$ 7,224				$ 6,950	$ 7,224	$ 6,950	$ 7,996
Restructuring charges	1,684	714	773	720	1,431	608	678	2,225	3,891	4,942	3,782
Restructuring liabilities									(4,841)	(4,694)	(3,888)
Adjustment to liability									(478)	24	(954)
Foreign currency translation adjustment										2	14
Closing Balance	5,796				7,224				5,796	7,224	6,950
Marketing & Events Group
Reconciliation of beginning and ending liability balances by major restructuring activity
Restructuring charges									(409)	3,479	3,756
Marketing & Events Group | Severance & Employee Benefits
Reconciliation of beginning and ending liability balances by major restructuring activity
Beginning Balance				720				831	720	831	1,106
Restructuring charges									2,931	2,506	1,182
Restructuring liabilities									(2,411)	(2,670)	(1,175)
Adjustment to liability									0	51	(294)
Foreign currency translation adjustment										2	12
Closing Balance	1,240				720				1,240	720	831
Marketing & Events Group | Facilities
Reconciliation of beginning and ending liability balances by major restructuring activity
Beginning Balance				5,571				4,819	5,571	4,819	5,051
Restructuring charges									(315)	2,346	2,519
Restructuring liabilities									(1,691)	(1,567)	(2,356)
Adjustment to liability									0	(27)	(397)
Foreign currency translation adjustment										0	2
Closing Balance	3,565				5,571				3,565	5,571	4,819
Other Restructuring | Severance & Employee Benefits
Reconciliation of beginning and ending liability balances by major restructuring activity
Beginning Balance				0				24	0	24	197
Restructuring charges									1,967	90	26
Restructuring liabilities									(498)	(114)	(199)
Adjustment to liability									(478)	0	0
Foreign currency translation adjustment										0	0
Closing Balance	991				0				991	0	24
Other Restructuring | Facilities
Reconciliation of beginning and ending liability balances by major restructuring activity
Beginning Balance				933				1,276	933	1,276	1,642
Restructuring charges									(692)	0	55
Restructuring liabilities									(241)	(343)	(158)
Adjustment to liability									0	0	(263)
Foreign currency translation adjustment										0	0
Closing Balance	$ 0				$ 933				$ 0	$ 933	$ 1,276