Revenue from Contracts with Customers (Summary of Remaining Performance Obligations/Backlog) (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Disaggregation Of Revenue [Line Items]
Estimated recognition of Backlog	$ 38,094
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Disaggregation Of Revenue [Line Items]
Estimated recognition of Backlog	$ 31,311
Revenue, remaining performance obligation, expected timing of satisfaction, period	6 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-07-01
Disaggregation Of Revenue [Line Items]
Estimated recognition of Backlog	$ 5,570
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-07-01
Disaggregation Of Revenue [Line Items]
Estimated recognition of Backlog	$ 786
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-07-01
Disaggregation Of Revenue [Line Items]
Estimated recognition of Backlog	$ 426
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-07-01
Disaggregation Of Revenue [Line Items]
Estimated recognition of Backlog	$ 1
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 year