Goodwill and Intangible Assets (Goodwill Segment) (Details) $ in Thousands	9 Months Ended
Sep. 30, 2016 USD ($)
Changes in goodwill
Balance at beginning of year	$ 510,985
Acquisitions	31,266
Foreign currency translation	(42,887)
Balance at end of year	499,364
Environmental and Nuclear
Changes in goodwill
Balance at beginning of year	64,764
Foreign currency translation	(1,230)
Balance at end of year	63,534
Energy and Industrial
Changes in goodwill
Balance at beginning of year	93,242
Acquisitions	5,003
Balance at end of year	98,245
Transportation
Changes in goodwill
Balance at beginning of year	281,520
Acquisitions	2,814
Foreign currency translation	(33,252)
Balance at end of year	251,082
Water
Changes in goodwill
Balance at beginning of year	71,459
Acquisitions	23,449
Foreign currency translation	(8,405)
Balance at end of year	$ 86,503

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.

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

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

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=64834752&loc=SL49117168-202975

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