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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

X

- 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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X

- 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

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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

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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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