Overview and Basis of Presentation - Impact of Adopting ASU 2017-07 on Condensed Consolidated Statement of Operations (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Corporate activities		$ 2,535	$ 2,920	$ 4,752	$ 5,461
Other expense	[1]	543	222	781	674
As Previously Reported
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Corporate activities			3,008		5,618
Services
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cost of services and products		280,842	281,909	538,137	562,547
Services | Reclassifications to Conform with Revenue Presentation
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cost of services and products			(2,841)		4,571
Services | As Previously Reported
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cost of services and products			284,884		558,493
Products
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cost of services and products		$ 44,433	43,329	$ 75,555	75,431
Products | Reclassifications to Conform with Revenue Presentation
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cost of services and products			2,841		(4,571)
Products | As Previously Reported
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cost of services and products			40,488		80,002
ASU 2017-07
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Corporate activities			(88)		(157)
Other expense			222		674
ASU 2017-07 | Services
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cost of services and products			$ (134)		$ (517)

[1] We adopted ASU 2017-07 on January 1, 2018, which requires retrospective adoption. As a result, we recorded the nonservice cost component of net periodic benefit cost within other expense for the three and six months ended June 30, 2018, and we reclassified $0.2 million from operating expenses to other expense for the three months ended June 30, 2017 and $0.7 million for the six months ended June 30, 2017 to conform with current period presentation. Refer to Note 1 – Overview and Basis of Presentation for additional details on the impact of this adoption on our Condensed Consolidated Statements of Operations.