CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY (DEFICIT) (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Common Stock Class A-1 Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2019			76,637,470
Beginning balance at Dec. 31, 2019	$ (43,010)		$ 8	$ 8,352		$ (51,370)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of A-2 common stock to A-1 common stock (in shares)			1,596,636
Conversion of Class A-2 Common Stock to Class A-1 Common Stock	19,160			19,160
Stock-based compensation	1,060			1,060
Net income	48,043					48,043
Ending balance (in shares) at Mar. 31, 2020			78,234,106
Ending balance at Mar. 31, 2020	25,253		$ 8	28,572		(3,327)
Beginning balance (in shares) at Dec. 31, 2019			76,637,470
Beginning balance at Dec. 31, 2019	(43,010)		$ 8	8,352		(51,370)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain (loss) on investments in convertible notes	0
Net income	8,110
Ending balance (in shares) at Sep. 30, 2020			92,146,013
Ending balance at Sep. 30, 2020	122,269		$ 9	165,520		(43,260)
Beginning balance (in shares) at Mar. 31, 2020			78,234,106
Beginning balance at Mar. 31, 2020	25,253		$ 8	28,572		(3,327)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)			148,299
Exercise of common stock options	359			359
Stock-based compensation	1,327			1,327
Net income	(46,768)					(46,768)
Ending balance (in shares) at Jun. 30, 2020			78,382,405
Ending balance at Jun. 30, 2020	(19,829)		$ 8	30,258		(50,095)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)			181,208
Exercise of common stock options	405			405
Exercise of warrants (in shares)		510
Exercise of warrants	4			4
Exchange of warrants for common stock (in shares)			5,581,890
Exchange of warrants for common stock	54,471			54,471
Stock-based compensation	1,668			1,668
Unrealized gain (loss) on investments in convertible notes	0
Issuance of common stock (in shares)			8,000,000
Issuance of common stock	78,715	$ 1		78,714
Net income	6,835					6,835
Ending balance (in shares) at Sep. 30, 2020			92,146,013
Ending balance at Sep. 30, 2020	122,269		$ 9	165,520		(43,260)
Beginning balance (in shares) at Dec. 31, 2020			93,379,508
Beginning balance at Dec. 31, 2020	127,871		$ 9	179,549	$ 93	(51,780)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,593			1,593
Unrealized gain (loss) on investments in convertible notes	469				469
Net income	1,501					1,501
Ending balance (in shares) at Mar. 31, 2021			93,379,508
Ending balance at Mar. 31, 2021	131,434		$ 9	181,142	562	(50,279)
Beginning balance (in shares) at Dec. 31, 2020			93,379,508
Beginning balance at Dec. 31, 2020	127,871		$ 9	179,549	93	(51,780)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain (loss) on investments in convertible notes	5,358
Net income	24,753
Ending balance (in shares) at Sep. 30, 2021			94,042,341
Ending balance at Sep. 30, 2021	164,144		$ 9	185,711	5,451	(27,027)
Beginning balance (in shares) at Mar. 31, 2021			93,379,508
Beginning balance at Mar. 31, 2021	131,434		$ 9	181,142	562	(50,279)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)			281,245
Exercise of common stock options	685			685
Stock-based compensation	2,148			2,148
Unrealized gain (loss) on investments in convertible notes	5,204				5,204
Net income	12,445					12,445
Ending balance (in shares) at Jun. 30, 2021			93,660,753
Ending balance at Jun. 30, 2021	151,916		$ 9	183,975	5,766	(37,834)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of common stock options (in shares)			381,588
Exercise of common stock options	770			770
Stock-based compensation	966			966
Unrealized gain (loss) on investments in convertible notes	(315)				(315)
Net income	10,807					10,807
Ending balance (in shares) at Sep. 30, 2021			94,042,341
Ending balance at Sep. 30, 2021	$ 164,144		$ 9	$ 185,711	$ 5,451	$ (27,027)