Fair Value Measurements (Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation) (Details) (Contingent Consideration Liability, USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Contingent Consideration Liability
Contingent consideration for acquisitions
Balance at beginning of period	$ (9,317)	$ (7,866)	$ (9,856)	$ (3,700)
Additions for acquisitions	0	(3,431)	0	(10,346)
Payments on contingent consideration	0	0	0	1,731
Settlements of contingent consideration	0	0	0	1,369
Fair value adjustment	1,038	62	1,408	19
Foreign currency translation adjustment	(129)	477	40	169
Balance at end of period	$ (8,408)	$ (10,758)	$ (8,408)	$ (10,758)