Fair Value Measurements (Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation) (Details) (Contingent Consideration Liability, USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Contingent Consideration Liability
Contingent consideration for acquisitions
Balance at beginning of period	$ 10,091	$ 10,800	$ 9,856	$ 3,700
Additions for acquisitions	0	0	0	6,876
Payments on contingent consideration	0	(1,731)	0	(1,731)
Settlements of contingent consideration	0	(1,369)	0	(1,369)
Fair value adjustment	(402)	0	(370)	0
Foreign currency translation adjustment	(372)	166	(169)	390
Balance at end of period	$ 9,317	$ 7,866	$ 9,317	$ 7,866