Fair Value Measurements. Cash Equivalents and Marketable Securities - Activity In Level 3 Instruments (Details) - Fair Value, Measurements, Recurring - Level 3 - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Redeemable Noncontrolling Interest
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value — beginning of period	$ 49,600	$ 41,800
Increase (decrease) in fair value	(3,027)	5,022
Net loss for the period	(1,073)	(322)
Fair value — end of period	45,500	46,500
Contingent consideration
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value — beginning of period	1,365	0
Increase (decrease) in fair value	(190)	0
Net loss for the period	0	0
Fair value — end of period	$ 1,175	$ 0

Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Net Income (Loss) For The Period

No definition available.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of increase (decrease) of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

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