Fair Value Measurements - Liability Measured on Recurring Basis, Unobservable Input Reconciliation (Details) - Contingent Consideration - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 93,204	$ 10,912	$ 82,236	$ 10,956
Contingent consideration liability recorded as the result of acquisitions	1,203	0	9,583	0
Fair value adjustments recorded to income	$ 273	$ (828)	$ 3,473	$ (741)
Fair Value, Recurring Basis, Unobservable Input Reconciliation, Liability, Gain (Loss), Statement of Income [Extensible List]	us-gaap:BusinessCombinationContingentConsiderationArrangementsContingentConsiderationBenefit	us-gaap:BusinessCombinationContingentConsiderationArrangementsContingentConsiderationBenefit	us-gaap:BusinessCombinationContingentConsiderationArrangementsContingentConsiderationBenefit	us-gaap:BusinessCombinationContingentConsiderationArrangementsContingentConsiderationBenefit
Contingent payments made	$ (15,072)	$ (53)	$ (15,684)	$ (184)
Ending balance	$ 79,608	$ 10,031	$ 79,608	$ 10,031

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

No definition available.

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- Definition

Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Amount of purchases 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)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Amount of settlements 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

+ Details

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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

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

Indicates line item in statement in which net income is reported that includes gain (loss) from liability measured at fair value using unobservable input (level 3).

+ References

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