Fair Value Measurement Fair Value Measurement (Reconciliation of Level 3 Liabilities) (Details) (Level 3 [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Balance, beginning of period	$ 11,726	$ 23,698	$ 17,054	$ 20,907	$ 20,907
Earnouts related to acquisitions	0	1,900	0	7,678	4,288
Payments of contingent purchase obligations	0	0	(4,804)	(2,407)	(2,407)
Adjustments to contingent purchase obligation	(3,171)	(3,169)	(3,695)	(3,749)	(5,734)
Balance, end of period	$ 8,555	$ 22,429	$ 8,555	$ 22,429	$ 17,054