Consolidated Entities - ISP Fund LP (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	May 31, 2021	May 20, 2021	Dec. 31, 2020
CONSOLIDATED ENTITIES
Total assets	$ 789,150		$ 789,150				$ 999,570	[1]
Changes in fair values of equity and long-term investments	45,315	$ 46,698	100,360	$ 68,613
Unrealized gain on equity investments			$ 99,046	$ 68,613
ISP Fund LP
CONSOLIDATED ENTITIES
Contributed to partnership for investing							300,000
Distribution from partnership					$ 110,000
Economic interest of the Partnership (in percent)			100.00%
Total assets	219,000		$ 219,000				$ 299,300
Investment-related expenses, net of investment-related income	900		1,300
Changes in fair values of equity and long-term investments	$ 25,200		$ 31,000
Commitment for future contribution						$ 110,000
Lock-up period			36 months

[1] Consolidated balance sheet as of December 31, 2020 has been derived from audited consolidated financial statements.