Marketable Securities - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investments, Debt and Equity Securities [Abstract]
Equity securities, gross unrealized gain	$ 170
Equity securities, gross unrealized loss		$ 956
Marketable securities, realized gains	483	317	$ 1,677
Marketable securities, realized loss	$ 151	$ 565	$ 1,390