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Acquisitions Of Businesses (Details) $ in Thousands	Nov. 01, 2017 Company	Mar. 01, 2017 USD ($) Company	Jan. 04, 2017 Company	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Goodwill				$ 965,046	$ 964,893
Number of businesses acquired | Company	1	1	1
2017 Acquisitions [Member]
Business Acquisition [Line Items]
Purchase price		$ 109,300
Working capital acquired		9,600
Other net assets		2,300
Goodwill		40,800
Identifiable intangible assets		$ 56,600

X

- Definition

The amount of acquisition cost of a business combination allocated to other net assets.

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The amount of acquisition cost of a business combination allocated to working capital.

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- Definition

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.

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- Definition

Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84161108&loc=d3e4845-128472

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- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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-Section 45
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The number of businesses acquired by the entity during the period.

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
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