Acquisitions (Details) $ in Thousands	3 Months Ended
Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($) business
Acquisitions [Line Items]
Holdback payments for prior year acquisitions	$ 444	$ 554
Payments for acquisitions, net of cash acquired	$ 444	$ 52,369
Small business distributors [Member]
Acquisitions [Line Items]
Number of businesses acquired \| business		2
2018 acquisitions [Member]
Acquisitions [Line Items]
Payments for acquisitions, net of cash acquired		$ 51,815

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

The number of businesses acquired by the entity during the period.

+ References

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- Definition

Cash outflow representing an adjustment to the purchase price of a previous acquisition.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3213-108585

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- Definition

The cash outflow associated with the acquisition of a business, net of the cash acquired from the purchase.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
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-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3213-108585

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