Earnings Per Share, as restated - Dilutive Potential Common Shares (Details) - USD ($) $ in Thousands				1 Months Ended			2 Months Ended	3 Months Ended	12 Months Ended
	Jul. 01, 2020	Nov. 01, 2018	May 16, 2013	Jan. 31, 2020	Sep. 30, 2019	Jul. 31, 2017	Feb. 28, 2021	Dec. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	May 31, 2020	May 29, 2020	May 18, 2020	Mar. 31, 2018	Apr. 30, 2017	Apr. 04, 2017
Earnings Per Share
Number of dilutive potential common stock									163,169,490	200,327,965	201,692,250
Convertible senior notes								$ 85,600	$ 85,600
Interest rate (as a percent)												3.50%
Stock options outstanding
Earnings Per Share
Options granted									3,509,549	3,221,892	2,679,667
3.75% Convertible Senior Notes
Earnings Per Share
Conversion of notes through common stock issuance							3,000,000.0
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%
7.5% Convertible Senior Note
Earnings Per Share
Conversion of notes through common stock issuance	16,000,000.0				16,000,000.0
Repurchase amount												$ 66,300
Principal amount					$ 40,000
Interest rate (as a percent)	7.50%				7.50%			7.50%	7.50%
5.5% Convertible Senior Notes
Earnings Per Share
Conversion of notes through common stock issuance								14,600,000
Convertible senior notes								$ 33,500	$ 33,500
Repurchase amount								33,500	33,500
Principal amount								$ 160	$ 160	$ 100,000				$ 100,000	$ 100,000
Interest rate (as a percent)								5.50%	5.50%			5.50%		5.50%	5.50%
Long-term debt												$ 48,700
Warrants issued in April 2017
Earnings Per Share
Shares of common stock that can be purchased from warrants issued (in shares)																55,286,696
Warrants issued in July 2017
Earnings Per Share
Shares of common stock that can be purchased from warrants issued (in shares)						55,286,696
Number of warrants exercised (in shares)						5,819,652
Warrants issued with the Amazon, Inc transaction agreement
Earnings Per Share
Shares of common stock that can be purchased from warrants issued (in shares)																	55,286,696
Series C redeemable convertible preferred stock.
Earnings Per Share
Shares issued (in shares)			10,431
Series E Preferred Stock
Earnings Per Share
Shares issued (in shares)		35,000
Number of preferred shares that had been converted to common stock				500						30,462
Number of shares redeemed										4,038
Stock options outstanding
Earnings Per Share
Number of dilutive potential common stock									10,284,498	23,013,590	21,957,150
Options granted									3,509,549	3,221,892	2,679,667
Restricted stock
Earnings Per Share
Number of dilutive potential common stock									5,874,642	4,608,560	2,347,347
Options granted									3,227,149	3,201,892	2,367,347
Common stock warrants
Earnings Per Share
Number of dilutive potential common stock									104,753,740	110,573,392	115,824,142
Preferred stock
Earnings Per Share
Number of dilutive potential common stock										2,998,527	17,933,591
Convertible Senior Notes
Earnings Per Share
Number of dilutive potential common stock									42,256,610	59,133,896	43,630,020