Organization and Summary of Significant Accounting Policies - Change in Accounting Estimate (Details) - Transportation |
12 Months Ended |
---|---|
Dec. 31, 2017 | |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] | |
Useful life | 10 years |
Scenario, Previously Reported | |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] | |
Useful life | 20 years |