Goodwill and Other Intangible Assets (Rollforward of Other Intangible Assets) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Other Intangible Assets [Line Items]
Other intangible assets, gross				$ 323,300
Accumulated amortization				(143,600)
Other Intangible Assets [Rollforward]
Other intangible assets, net, beginning balance		$ 179,711
Amortization expense		(4,100)	$ (5,300)
Currency translation adjustments, other intangible assets		400
Other intangible assets, net, ending balance		176,031
Customer Relationships and Backlog [Member]
Other Intangible Assets [Line Items]
Other intangible assets, amortizing, gross				195,100
Accumulated amortization				(131,900)
Other Intangible Assets [Rollforward]
Other intangible assets, net, amortizing, beginning balance		63,200
Amortization expense		(3,800)
Currency translation adjustments, amortizing intangible assets		100
Other intangible assets, net, amortizing, ending balance		59,500
Other Amortizing Intangible Assets [Member]
Other Intangible Assets [Line Items]
Other intangible assets, amortizing, gross	[1]			19,100
Accumulated amortization	[1]			(11,700)
Other Intangible Assets [Rollforward]
Other intangible assets, net, amortizing, beginning balance	[1]	7,400
Amortization expense	[1]	(300)
Currency translation adjustments, amortizing intangible assets	[1]	0
Other intangible assets, net, amortizing, ending balance	[1]	7,100
Trade Names [Member]
Other Intangible Assets [Line Items]
Other intangible assets, non-amortizing, carrying amount		34,500		34,500
Other Intangible Assets [Rollforward]
Other intangible assets, non-amortizing, beginning balance		34,500
Currency translation adjustments, non-amortizing intangible assets		0
Other intangible assets, non-amortizing, ending balance		34,500
Pre-Qualifications [Member]
Other Intangible Assets [Line Items]
Other intangible assets, non-amortizing, carrying amount		74,600		$ 74,600
Other Intangible Assets [Rollforward]
Other intangible assets, non-amortizing, beginning balance		74,600
Currency translation adjustments, non-amortizing intangible assets		300
Other intangible assets, non-amortizing, ending balance		$ 74,900

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