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Goodwill and Identifiable Assets (Goodwill) (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Sep. 30, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Goodwill [Roll Forward] |  |  |
Gross goodwill | $ 875,714 | $ 512,060 | $ 514,426
Goodwill | 875,714 | 512,060 |
Translation adjustment | (910) | (2,366) |
Apex |  |  |
Goodwill [Roll Forward] |  |  |
Gross goodwill | 645,448 | 287,951 | 289,712
Translation adjustment | (963) | (1,761) |
Oxford |  |  |
Goodwill [Roll Forward] |  |  |
Gross goodwill | 230,266 | 224,109 | $ 224,714
Translation adjustment | 53 | $ (605) |
Creative Circle [Member] |  |  |
Goodwill [Roll Forward] |  |  |
Goodwill, Acquired During Period | 358,460 |  |
Creative Circle [Member] | Apex |  |  |
Goodwill [Roll Forward] |  |  |
Goodwill, Acquired During Period | 358,460 |  |
Creative Circle [Member] | Oxford |  |  |
Goodwill [Roll Forward] |  |  |
Goodwill, Acquired During Period | 0 |  |
LabResource [Member] |  |  |
Goodwill [Roll Forward] |  |  |
Goodwill, Acquired During Period | 6,104 |  |
LabResource [Member] | Apex |  |  |
Goodwill [Roll Forward] |  |  |
Goodwill, Acquired During Period | 0 |  |
LabResource [Member] | Oxford |  |  |
Goodwill [Roll Forward] |  |  |
Goodwill, Acquired During Period | $ 6,104 |  |

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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 -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 + Details
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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 (a) -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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- 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 + Details
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