Recent Accounting Pronouncements Accounting Pronouncements - Narrative (Details) - Accounting Standards Update 2014-09 - USD ($) |
3 Months Ended | 9 Months Ended | |
|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2018 |
Jan. 01, 2018 |
|
| New Accounting Pronouncements or Change in Accounting Principle [Line Items] | |||
| Increase in cost of goods and services sold | $ 73,600,000 | $ 202,400,000 | |
| Cumulative effect of new accounting principle in period of adoption | $ 0 | ||
| Increase in other current assets | 1,400,000 | 1,400,000 | |
| Decrease In accounts receivable | 1,400,000 | 1,400,000 | |
| Voyage charter revenues | |||
| New Accounting Pronouncements or Change in Accounting Principle [Line Items] | |||
| Increase in voyage charter revenue | $ 73,600,000 | $ 202,400,000 |