STATEMENTS OF CHANGES IN PREFERRED STOCK AND STOCKHOLDERS' DEFICIT - 6 months ended Jun. 30, 2018 - USD ($) $ in Thousands	Total	Common Stock	Additional Paid In Capital Common Stock	Accumulated Deficit	Series 1 Preferred Stock - Mezzanine
Balance at Dec. 31, 2017	$ (96,806)	$ 143	$ 615,493	$ (712,442)	$ 143,992
Balance (in shares) at Dec. 31, 2017		142,658,037			119,644
Adjustment for implementation of ASU No. 2014-09, Revenue from Contracts with Customers	(8,131)			(8,131)
Stock-based compensation	5,370		5,370
Exercise of employee stock options	$ 240		240
Exercise of employee stock options (Share)	104,167	104,166
Cancelled restricted common stock	$ 0	$ 0	0	0	$ 0
Cancelled restricted common stock (shares)		(70,867)
Repurchase of restricted common stock	(1,275)	$ (1)	(1,274)
Repurchase of restricted common stock (shares)		(311,566)
Preferred stock dividends					$ 10,436
Preferred stock dividends	(10,582)		(10,582)
Preferred stock dividends (shares)					7,358
Net loss	(28,051)			(28,051)
Balance at Jun. 30, 2018	$ (139,235)	$ 142	$ 609,247	$ (748,624)	$ 154,428
Balance (in shares) at Jun. 30, 2018		142,379,770			127,002