Fair Value Measurements (Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Contingent consideration for acquisitions
Balance at beginning of period	$ (21,594)	$ (3,000)	$ (20,981)	$ (3,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	0	(13,814)	0	(13,814)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Payments		0	15,751	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	0	512	613	512
Balance at end of period	$ (5,843)	$ (17,326)	$ (5,843)	$ (17,326)