Fair Value Measurements Fair Value, Reconciliation of Level 3 - Liabilities (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		$ 77,484	$ 123,424	$ 77,484	$ 123,424	$ 81,439	$ 82,584	$ 125,018	$ 130,725
Contingent Consideration, Beginning Value		0	14,788	14,588	10,781
Contingent Consideration, Reclass		0	0	(6,778)	(285)
(Gain) loss, net from changes in fair value of contingent consideration	[1]	0	(162)	48	4,130
Contingent Consideration, Ending Value		0	14,626	0	14,626
Fair Value, Measurement with Unobservable Inputs, Unrealized Gain Loss	[2]	0	(162)	0	4,004
Convertible debt securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value		$ 11,232	$ 9,931	$ 11,232	$ 9,931	$ 10,868	$ 10,038	$ 10,573	$ 10,116

[1] Changes in the fair value of contingent consideration liabilities are classified within "Acquisition-related expense (benefit), net" on the condensed consolidated statements of operations.

[2] Represents the unrealized losses or gains recorded in earnings and/or other comprehensive income (loss) during the period for assets and liabilities classified as Level 3 that are still held (or outstanding) at the end of the period.