Fair Value Measurements - Level 3 Contingent Purchase Price (Details) - Contingent Purchase Price Liability - Fair Value, Measurements, Recurring - Significant Unobservable Inputs (Level 3) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 124,735	$ 119,612	$ 137,289	$ 123,757
Payments	(936)	(4,474)	(22,002)	(7,247)
Fair value adjustments to contingent purchase prices included in net loss	(12,628)	3,433	(4,116)	2,061
Balance at end of period	$ 111,171	$ 118,571	$ 111,171	$ 118,571