Nature of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended						3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Feb. 28, 2021	Jan. 31, 2021	Nov. 30, 2020	Aug. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 31, 2020	May 29, 2020	May 18, 2020
Liquidity
Public offerings, common stock, net (in shares)			43,700,000	35,276,250	46,000,000	10,000,000	4,400,000												79,000,000.0
Share Price			$ 22.25	$ 10.25	$ 2.75	$ 2.35					$ 2.75			$ 2.35						$ 2.75
Proceeds from public offerings, net of transaction costs			$ 927,300	$ 344,400	$ 120,400	$ 23,500								$ 23,498	$ (269)	$ 28,265	$ 344,398	$ 38,098	$ 1,271,714	$ 158,343	$ 7,195
Common stock, shares issued					318,637,560	244,537,235	473,977,469	406,123,816	348,201,792	322,220,469	318,637,560	253,982,578	246,975,173	244,537,235	348,201,792	246,975,173	406,123,816	253,982,578	473,977,469	318,637,560
Cash and cash equivalents					$ 139,496	$ 39,336	$ 1,312,404	$ 448,140	$ 152,492	$ 74,340	$ 139,496	$ 43,275	$ 19,845	$ 39,336	$ 152,492	$ 19,845	$ 448,140	$ 43,275	$ 1,312,404	$ 139,496
Restricted cash							321,900												321,900
Net loss attributable to common shareholders							(484,105)	(65,217)	(9,414)	(37,445)	(19,277)	(18,366)	(17,351)	(30,560)	(46,859)	(47,911)	(112,076)	(66,277)	(596,181)	(85,555)	(85,660)
Net loss attributable to common shareholders							484,105	65,217	9,414	37,445	19,277	18,366	17,351	30,560	46,859	47,911	112,076	66,277	596,181	85,555	85,660
Net cash used in operating activities										60,402				35,699	111,891	48,328	156,506	54,141	155,476	53,324	$ 58,350
Accumulated deficit					(1,350,307)	(1,297,072)	(1,946,488)	(1,462,377)	(1,397,160)	(1,387,752)	(1,350,307)	(1,332,259)	(1,314,425)	(1,297,072)	(1,397,160)	(1,314,425)	(1,462,377)	(1,332,259)	(1,946,488)	(1,350,307)
Total operating lease, liabilities							113,938												113,938
Total finance lease liabilities							5,396												5,396
Operating lease liabilities					9,428	7,042	14,314	10,609	9,453	8,959	9,428	8,666	7,512	7,042	9,453	7,512	10,609	8,666	14,314	9,428
Finance lease liabilities					$ 226	$ 236	903	$ 374	$ 345	$ 204	$ 226	$ 310	$ 266	$ 236	$ 345	$ 266	$ 374	$ 310	903	$ 226
Incremental term loan							175,400												175,400
Short-term borrowing							25,400												25,400
Convertible senior notes							85,600												85,600
Working capital																			1,400,000
Interest rate (as a percent)																						3.50%
Finance obligation
Liquidity
Total finance lease liabilities							181,553												181,553
Finance lease liabilities							$ 32,700												$ 32,700
3.75% Convertible Senior Notes
Liquidity
Share Price							$ 33.91												$ 33.91
Principal amount							$ 212,463												$ 212,463			$ 212,463	$ 12,500	$ 200,000
Interest rate (as a percent)							3.75%												3.75%			3.75%	3.75%	3.75%
Private placement | 3.75% Convertible Senior Notes
Liquidity
Principal amount																						$ 212,500
Interest rate (as a percent)																						3.75%
Subsequent event
Liquidity
Public offerings, common stock, net (in shares)	54,966,188
Subsequent event | 3.75% Convertible Senior Notes
Liquidity
Interest rate (as a percent)	3.75%	3.75%
Subsequent event | SK Holdings Co LTD
Liquidity
Public offerings, common stock, net (in shares)	54,996,188
Proceeds from public offerings, net of transaction costs	$ 1,600,000
Common stock, shares issued	54,966,188
Per share price of shares of common stock	$ 29.2893
Subsequent event | Public Offerings
Liquidity
Public offerings, common stock, net (in shares)	32,200,000	32,200,000
Share Price	$ 65.00	$ 65.00
Proceeds from public offerings, net of transaction costs	$ 1,800,000	$ 1,800,000