Interest and Other Investment Income (Loss), Net (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Interest and Other Income [Abstract]
Interest on loans receivable	$ 560	$ 1,426
Interest on cash and cash equivalents and restricted cash	62	3,966
Credit losses on loans receivable	0	(7,261)
Market-to-market decrease in the fair value of marketable security (sold on January 23, 2020)	0	(4,938)
Other, net	900	903
Interest and other investment income (loss), net	$ 1,522	$ (5,904)