Fair Value Measurement Fair Value Measurement (Reconciliation of Level 3 Liabilities) (Details) - Level 3 [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Balance, beginning of period	$ 3,481	$ 11,726	$ 7,665	$ 17,054	$ 17,054
Earnouts related to acquisitions	4,114	0	4,114	0	0
Payments of contingent purchase obligations	0	0	3,317	4,804	4,804
Adjustments to contingent purchase obligation	57	(3,171)	(810)	(3,695)	(4,585)
Balance, end of period	$ 7,652	$ 8,555	$ 7,652	$ 8,555	$ 7,665