Fair Value Measurements - Reconciles Net Loss to Unrealized Loss on Equity Securities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Fair Value Disclosures [Abstract]
Net gain (loss) recognized during the period on equity securities	$ 0	$ 0	$ 0	$ (8,285)
Less: Net gain (loss) recognized during the period on equity securities sold during the period	0	0	0	(8,285)
Unrealized gain (loss) loss recognized during the reporting period on equity securities still held at the reporting date	$ 0	$ 0	$ 0	$ 0