Goodwill and Other Intangible Assets (Rollforward of Other Intangible Assets) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Other Intangible Assets [Line Items]
Other intangible assets, gross carrying amount, as of December 31, 2015						$ 329,300
Accumulated amortization						(129,900)
Other Intangible Assets [Rollforward]
Other intangible assets, net, beginning balance				$ 199,379
Amortization expense		$ (5,200)	$ (6,900)	(15,700)	$ (21,500)
Currency translation adjustments, other intangible assets				2,800
Other intangible assets, net, ending balance		186,515		186,515
Customer Relationships and Backlog [Member]
Other Intangible Assets [Line Items]
Other intangible assets, amortizing, gross carrying amount, as of December 31, 2015						195,400
Accumulated amortization						(114,600)
Other Intangible Assets [Rollforward]
Other intangible assets, net, amortizing, beginning balance				80,800
Amortization expense				(13,200)
Currency translation adjustments, amortizing intangible assets				500
Other intangible assets, net, amortizing, ending balance		68,100		68,100
Other Amortizing Intangible Assets [Member]
Other Intangible Assets [Line Items]
Other intangible assets, amortizing, gross carrying amount, as of December 31, 2015	[1]					25,700
Accumulated amortization	[1]					(15,300)
Other Intangible Assets [Rollforward]
Other intangible assets, net, amortizing, beginning balance	[1]			10,400
Amortization expense	[1]			(2,500)
Currency translation adjustments, amortizing intangible assets	[1]			100
Other intangible assets, net, amortizing, ending balance	[1]	8,000		8,000
Trade Names [Member]
Other Intangible Assets [Line Items]
Other intangible assets, non-amortizing, carrying amount, as of December 31, 2016		34,800		34,800		34,800
Other Intangible Assets [Rollforward]
Other intangible assets, non-amortizing, beginning balance				34,800
Currency translation adjustments, non-amortizing intangible assets				0
Other intangible assets, non-amortizing, ending balance		34,800		34,800
Pre-Qualifications [Member]
Other Intangible Assets [Line Items]
Other intangible assets, non-amortizing, carrying amount, as of December 31, 2016		75,600		73,400		$ 73,400
Other Intangible Assets [Rollforward]
Other intangible assets, non-amortizing, beginning balance				73,400
Currency translation adjustments, non-amortizing intangible assets				2,200
Other intangible assets, non-amortizing, ending balance		$ 75,600		$ 75,600

[1] Consists principally of trade names and non-compete agreements.