Segment Information - Reconciliation of Income Statement Items from Reportable Segments (Parenthetical) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Other expense	[1]	$ 543	$ 222	$ 781	$ 674
ASU 2017-07
Segment Reporting Information [Line Items]
Other expense			$ 222		$ 674

[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.