Investments - Short-Term Investments (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Marketable securities	$ 155		$ 155		$ 220
Unrealized gain (loss)	77	$ (226)	(20)	$ 0
Steel Excel
Debt Securities, Available-for-sale [Line Items]
Securities sold during the period	$ 1,135	$ 0	$ 2,327	$ 0