Earnings Per Share - Dilutive Potential Common Shares (Details) - USD ($) $ in Thousands					1 Months Ended		3 Months Ended					12 Months Ended
	Jan. 07, 2021	Jul. 01, 2020	Nov. 01, 2018	May 16, 2013	Jan. 31, 2021	Sep. 30, 2019	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	May 31, 2020	May 29, 2020	May 18, 2020	Mar. 31, 2018	Jul. 31, 2017	Jul. 20, 2017	Apr. 30, 2017	Apr. 04, 2017
Earnings Per Share
Number of dilutive potential common stock												147,846,729	163,169,490	200,327,965
Convertible senior notes							$ 192,600					$ 192,600
3.75% Convertible Senior Notes
Earnings Per Share
Principal amount							$ 197,278			$ 15,200		$ 197,278			$ 212,463	$ 12,500	$ 200,000
Conversion of notes through common stock issuance							0	0	0	3,016,036		3,000,000.0
Interest rate (as a percent)							3.75%			3.75%	3.75%	3.75%	3.75%		3.75%	3.75%	3.75%
7.5% Convertible Senior Note
Earnings Per Share
Principal amount						$ 40,000
Conversion of notes through common stock issuance		16,000,000.0				16,000,000.0
Interest rate (as a percent)		7.50%				7.50%					7.50%		7.50%
5.5% Convertible Senior Notes
Earnings Per Share
Principal amount	$ 160,000				$ 160						$ 33,500		$ 33,500					$ 100,000
Conversion of notes through common stock issuance	69,808				69,808						14,600,000
Repurchase amount											$ 33,500		$ 33,500		$ 66,300
Interest rate (as a percent)	5.50%				5.50%		5.50%				5.50%	5.50%	5.50%		5.50%		5.50%	5.50%
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	55,286,696
Number of warrants exercised (in shares)												17,461,994	0
Warrants issued with the Walmart Stores, Inc transaction agreement
Earnings Per Share
Shares of common stock that can be purchased from warrants issued (in shares)							20,368,782					20,368,782							55,286,696	55,286,696
Number of warrants exercised (in shares)												13,094,217	5,819,652
Series C redeemable convertible preferred stock.
Earnings Per Share
Temporary Equity, Stock Issued During Period, Shares, New Issues				10,431
Series E Preferred Stock
Earnings Per Share
Temporary Equity, Stock Issued During Period, Shares, New Issues			35,000
Number of shares redeemed													4,038
Stock options
Earnings Per Share
Number of dilutive potential common stock												23,806,909	10,284,498	23,013,590
Options granted												16,502,335	3,509,549	3,221,892
Restricted stock outstanding
Earnings Per Share
Number of dilutive potential common stock												4,851,873	5,874,642	4,608,560
Options granted												1,894,356	3,227,149	3,201,892
Warrant
Earnings Per Share
Number of dilutive potential common stock												80,017,181	104,753,740	110,573,392
Preferred stock
Earnings Per Share
Number of dilutive potential common stock														2,998,527
Convertible senior notes
Earnings Per Share
Number of dilutive potential common stock												39,170,766	42,256,610	59,133,896