Interest and Other Investment Income (Loss), Net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Interest and Other Income [Abstract]
Interest on loans receivable	$ 558	$ 810	$ 1,118	$ 2,236
Interest on cash and cash equivalents and restricted cash	78	1,498	140	5,464
Credit losses on loans receivable	0	(6,108)	0	(13,369)
Market-to-market decrease in the fair value of marketable security (sold on January 23, 2020)	0	0	0	(4,938)
Other, net	903	907	1,803	1,810
Interest and other investment income (loss), net	$ 1,539	$ (2,893)	$ 3,061	$ (8,797)