Fair Value Measurements - Summary of Gain (Loss) Derivative Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value adjustments, net	$ 16,030	$ 3,638	$ (864)
Unrealized gain (loss) on equity securities	15,348	(5,019)	0
Realized gain (loss) on equity securities	860	7,964	1,356
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unrealized Gain (Loss) on Securities	15,348	(5,019)	0
Realized gain (loss) on equity securities	860	7,964	0
Zinc Options
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net derivative gain (loss)	0		0
Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value adjustments, net	$ (178)	$ (60)	$ 0