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Goodwill and Identifiable Assets (Goodwill) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Roll Forward]
Gross goodwill	$ 875,657	$ 874,906	$ 512,060
Goodwill	875,657	874,906
Translation adjustment	751	(1,632)
Apex
Goodwill [Roll Forward]
Gross goodwill	644,972	644,617	287,951
Translation adjustment	355	(1,363)
Oxford
Goodwill [Roll Forward]
Gross goodwill	230,685	230,289	$ 224,109
Translation adjustment	$ 396	(269)
Creative Circle [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		358,029
Creative Circle [Member] | Apex
Goodwill [Roll Forward]
Goodwill, Acquired During Period		358,029
Creative Circle [Member] | Oxford
Goodwill [Roll Forward]
Goodwill, Acquired During Period		0
LabResource [Member]
Goodwill [Roll Forward]
Goodwill, Acquired During Period		6,449
LabResource [Member] | Apex
Goodwill [Roll Forward]
Goodwill, Acquired During Period		0
LabResource [Member] | Oxford
Goodwill [Roll Forward]
Goodwill, Acquired During Period		$ 6,449

X

- 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
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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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 (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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X

- 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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- Definition

Amount of increase (decrease) from foreign currency translation adjustments 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 (f)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

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