Fair Value Measurements - Schedule of Changes in Level 3 Liabilities (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Dividend income from investments in preferred stock		$ 48	$ 14,841	$ 16,756
Proceeds from sales of equity securities	$ (21,587)	(23,456)	(217)	(235)
Significant Unobservable Inputs (Level 3)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance		191	161,225
Retained interest in deconsolidated subsidiary		14,239	0
Dividend income from investments in preferred stock		48	14,841
Net unrealized appreciation (depreciation) in the fair value of the investments in equity securities and preferred stock		7,446	(17,499)
Return of preferred stock		0	(158,376)
Proceeds from sales of equity securities		(21,587)	0
Proceeds to be received from preferred stock		(337)	0
Ending balance		$ 0	$ 191	$ 161,225