Property, Plant and Equipment - Narrative (Details) - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Property, Plant and Equipment [Line Items] | ||
| Amortization expense on assets recorded under capital leases | $ 1,700 | |
| Accumulated depreciation and amortization, capital lease assets | 231,062 | $ 222,752 |
| Related Party | ||
| Property, Plant and Equipment [Line Items] | ||
| Accumulated depreciation and amortization, capital lease assets | 9,000 | 8,000 |
| Non-Related Party | ||
| Property, Plant and Equipment [Line Items] | ||
| Accumulated depreciation and amortization, capital lease assets | $ 6,900 | $ 6,300 |