Properties, Plant and Equipment - Other Property, Plant and Equipment - Depreciation and Amortization (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Properties, Plant and Equipment | |||
| Depreciation and amortization of other property, plant and equipment | $ 1.2 | $ 1.3 | $ 1.1 |