Summary of Significant Accounting Policies - Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair value measured on recurring basis \| Quoted prices in active markets (Level 1)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money Market Funds	$ 0	$ 0
Trading securities	9,582	10,168
Derivative Assets	0
Derivative Liabilities	0	0
Fair value measured on recurring basis \| Significant other observable inputs (Level 2)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money Market Funds	9,194	13,653
Trading securities	549	564
Derivative Assets	5,388
Derivative Liabilities	23,506	9,756
Fair value measured on recurring basis \| Significant unobservable inputs (Level 3)
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money Market Funds	0	0
Trading securities	0	0
Derivative Assets	0
Derivative Liabilities	0	0
Estimate of Fair Value Measurement \| Fair value measured on recurring basis
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Money Market Funds	9,194	13,653
Trading securities	10,131	10,732
Derivative Assets	5,388
Derivative Liabilities	23,506	9,756
OSG Investment
Assets and Liabilities Carried at Fair Value Measured on a Recurring Basis [Line Items]
Carrying value of investment	$ 14,316	$ 18,570

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

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Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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