Investment in Unconsolidated Entities - Cash Received and Distributions (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
NewINK Joint Venture
Schedule of Equity Method Investments [Line Items]
Cash generated from other activities and excess cash	$ 411	$ 874	$ 411	$ 1,593
Total	411	874	411	1,593
Inland Joint Venture
Schedule of Equity Method Investments [Line Items]
Cash generated from other activities and excess cash	0	950	0	1,250
Total	$ 0	$ 950	$ 0	$ 1,250

Amount of increase (decrease) in cash and cash equivalents. Cash and cash equivalents are the amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Includes effect from exchange rate changes.

No definition available.

Name:	us-gaap_CashAndCashEquivalentsPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration