Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Property, Plant and Equipment [Line Items] | |||
| Amortization expense on assets recorded under capital leases | $ 800 | $ 1,500 | $ 1,700 |
| Accumulated depreciation and amortization, capital lease assets | 284,287 | 242,623 | |
| Related Party | |||
| Property, Plant and Equipment [Line Items] | |||
| Accumulated depreciation and amortization, capital lease assets | 800 | 3,600 | |
| Non-Related Party | |||
| Property, Plant and Equipment [Line Items] | |||
| Accumulated depreciation and amortization, capital lease assets | $ 8,300 | $ 4,700 | |