Earnings Per Share - Anti-dilutive Shares (Details) - USD ($) $ / shares in Units, $ in Thousands					1 Months Ended	3 Months Ended		9 Months Ended
		Oct. 15, 2019	Nov. 01, 2018	May 16, 2013	Apr. 30, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2018	Jul. 31, 2017	Jul. 20, 2017	Apr. 04, 2017
Earnings Per Share
Number of dilutive potential common stock								217,909,307	186,714,827
Number of warrants exercised (in shares)		5,250,750
Exercise price of warrants (in dollars per share)												$ 2.1231
Principal amount						$ 100,000		$ 100,000
Convertible Senior Notes
Earnings Per Share
Principal amount						$ 40,000		$ 40,000
Interest rate (as a percent)						7.50%		7.50%
$40M Convertible Senior Note
Earnings Per Share
Principal amount						$ 40,000		$ 40,000
Interest rate (as a percent)						7.50%		7.50%
$100M Convertible Senior Notes
Earnings Per Share
Principal amount						$ 100,000		$ 100,000		$ 100,000
Interest rate (as a percent)						5.50%		5.50%		5.50%
Warrants issued in April 2017
Earnings Per Share
Number of warrants issued (in shares)					5,250,750
Exercise price of warrants (in dollars per share)					$ 2.69	$ 0		$ 0
Warrants issued with the Amazon.com, Inc transaction agreement
Earnings Per Share
Shares of common stock that can be purchased from warrants issued (in shares)													55,286,696
Exercise price of warrants (in dollars per share)						0		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)												55,286,696
Warrants issued with the Walmart transaction agreement
Earnings Per Share
Shares of common stock that can be purchased from warrants issued (in shares)											55,286,696
Exercise price of warrants (in dollars per share)						$ 0		$ 0
Series C Preferred Stock
Earnings Per Share
Stock options granted				10,431
Conversion of preferred stock (in shares)								7,811	7,811
Series E Preferred Stock
Earnings Per Share
Conversion of preferred stock (in shares)			35,000					6,731
Stock options
Earnings Per Share
Number of dilutive potential common stock	[1]							23,597,871	22,111,243
Stock options granted						2,572,500	2,170,000	2,936,892	2,654,667
Restricted stock
Earnings Per Share
Number of dilutive potential common stock	[2]							4,333,560	2,367,347
Stock options granted						2,562,500	2,160,000	2,926,892	2,367,347
Warrants
Earnings Per Share
Number of dilutive potential common stock	[3]							115,824,142	115,824,142
Preferred stock
Earnings Per Share
Number of dilutive potential common stock								15,019,838	2,782,075
Convertible Senior Notes
Earnings Per Share
Number of dilutive potential common stock								59,133,896	43,630,020

[1] During the three months ended September 30, 2019 and 2018, the Company granted 2,572,500 and 2,170,000 stock options, respectively. During the nine months ended September 30, 2019 and 2018, the Company granted 2,936,892, and 2,654,667 stock options, respectively.

[2] During the three months ended September 30, 2019 and 2018, the Company granted 2,562,500 and 2,160,000 shares of restricted stock, respectively. During the nine months ended September 30, 2019 and 2018, the Company granted 2,926,892 and 2,367,347 shares of restricted stock, respectively.

[3] In April 2017, the Company issued 5,250,750 warrants with an exercise price of $2.69 per warrant, as described in Note 9, Stockholders’ Equity. Of these warrants issued in April 2017, none had been exercised as of September 30, 2019. All of these warrants were exercised on October 15, 2019.In April 2017, the Company issued warrants to acquire up to 55,286,696 of the Company’s common stock as part of a transaction agreement, subject to certain vesting events, as described in Note 11, Warrant Transaction Agreements. Of these warrants issued, none had been exercised as of September 30, 2019.In July 2017, the Company issued warrants to acquire up to 55,286,696 of the Company’s common stock as part of a transaction agreement, subject to certain vesting events, as described in Note 11, Warrant Transaction Agreements. Of these warrants issued, none had been exercised as of September 30, 2019.