CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDER'S EQUITY (DEFICIT) - USD ($) $ in Thousands	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Earnings (Deficit)	Total
Balance at Dec. 31, 2019	$ 1,432,736	$ (449)	$ (12,366,909)	$ (10,934,622)
Increase (Decrease) in Stockholder's Equity
Non-cash, stock-based compensation	6,953			6,953
Change in unrealized holding gains (losses) on available-for-sale debt securities, net		(11)		(11)
Foreign currency translation		(352)		(352)
Net income (loss)			244,153	244,153
Balance at Mar. 31, 2020	1,439,689	(812)	(12,122,756)	(10,683,879)
Balance at Dec. 31, 2019	1,432,736	(449)	(12,366,909)	(10,934,622)
Increase (Decrease) in Stockholder's Equity
Net income (loss)				1,069,006
Balance at Sep. 30, 2020	1,452,849	(893)	(11,297,903)	(9,845,947)
Balance at Mar. 31, 2020	1,439,689	(812)	(12,122,756)	(10,683,879)
Increase (Decrease) in Stockholder's Equity
Non-cash, stock-based compensation	3,333			3,333
Change in unrealized holding gains (losses) on available-for-sale debt securities, net		11		11
Foreign currency translation		30		30
Net income (loss)			374,980	374,980
Balance at Jun. 30, 2020	1,443,022	(771)	(11,747,776)	(10,305,525)
Increase (Decrease) in Stockholder's Equity
Non-cash, stock-based compensation	9,827			9,827
Change in unrealized holding gains (losses) on available-for-sale debt securities, net		10		10
Foreign currency translation		(132)		(132)
Net income (loss)			449,873	449,873
Balance at Sep. 30, 2020	1,452,849	(893)	(11,297,903)	(9,845,947)
Balance at Dec. 31, 2020	1,463,407	(805)	(10,782,607)	(9,320,005)
Increase (Decrease) in Stockholder's Equity
Non-cash, stock-based compensation	7,676			7,676
Change in unrealized holding gains (losses) on available-for-sale debt securities, net		(2)		(2)
Foreign currency translation		(195)		(195)
Net income (loss)			424,527	424,527
Balance at Mar. 31, 2021	1,471,083	(1,002)	(10,358,080)	(8,887,999)
Balance at Dec. 31, 2020	1,463,407	(805)	(10,782,607)	(9,320,005)
Increase (Decrease) in Stockholder's Equity
Net income (loss)				1,287,899
Balance at Sep. 30, 2021	1,469,482	(1,218)	(9,494,708)	(8,026,444)
Balance at Mar. 31, 2021	1,471,083	(1,002)	(10,358,080)	(8,887,999)
Increase (Decrease) in Stockholder's Equity
Non-cash, stock-based compensation	(8,344)			(8,344)
Change in unrealized holding gains (losses) on available-for-sale debt securities, net		(6)		(6)
Foreign currency translation		(144)		(144)
Net income (loss)			476,743	476,743
Balance at Jun. 30, 2021	1,462,739	(1,152)	(9,881,337)	(8,419,750)
Increase (Decrease) in Stockholder's Equity
Non-cash, stock-based compensation	6,743			6,743
Change in unrealized holding gains (losses) on available-for-sale debt securities, net		(42)		(42)
Foreign currency translation		(24)		(24)
Net income (loss)			386,629	386,629
Balance at Sep. 30, 2021	$ 1,469,482	$ (1,218)	$ (9,494,708)	$ (8,026,444)