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Goodwill and Identifiable Assets (Goodwill) (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015
Goodwill [Roll Forward] |  |
Gross goodwill, period start | $ 874,906 | $ 512,060
Translation adjustment | (1,393) | (1,632)
Gross goodwill, period end | 873,513 | 874,906
Creative Circle [Member] |  |
Goodwill [Roll Forward] |  |
Goodwill, Acquired During Period |  | 358,029
LabResource [Member] |  |
Goodwill [Roll Forward] |  |
Goodwill, Acquired During Period |  | 6,449
Apex |  |
Goodwill [Roll Forward] |  |
Gross goodwill, period start | (644,617) | 287,951
Translation adjustment | 0 | (1,363)
Gross goodwill, period end | (644,617) | (644,617)
Apex | Creative Circle [Member] |  |
Goodwill [Roll Forward] |  |
Goodwill, Acquired During Period |  | 358,029
Apex | LabResource [Member] |  |
Goodwill [Roll Forward] |  |
Goodwill, Acquired During Period |  | 0
Oxford |  |
Goodwill [Roll Forward] |  |
Gross goodwill, period start | (230,289) | 224,109
Translation adjustment | (1,393) | (269)
Gross goodwill, period end | $ (228,896) | (230,289)
Oxford | Creative Circle [Member] |  |
Goodwill [Roll Forward] |  |
Goodwill, Acquired During Period |  | 0
Oxford | LabResource [Member] |  |
Goodwill [Roll Forward] |  |
Goodwill, Acquired During Period |  | $ 6,449

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- Definition Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination. + 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 (b) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
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- Definition Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits 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 (f) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
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- Definition Amount before 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,h) -URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267 + Details
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