Condensed Consolidated Statements of Changes in Stockholders' Equity - 6 months ended Jun. 30, 2018 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balances at Dec. 31, 2017	$ 814,977	$ 1,856	$ 3,357,345	$ (2,546,743)	$ 2,519
Balances, in shares at Dec. 31, 2017		185,638
Increase (Decrease) in Stockholders' Equity [Roll Forward]
NET INCOME (LOSS)	4,171			4,171
Other comprehensive income (loss)	(365)				(365)
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		1,436
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	(12)	$ 15	(27)
Balances at Jun. 30, 2018	818,771	$ 1,871	$ 3,357,318	(2,539,968)	(450)
Balances, in shares at Jun. 30, 2018		187,074
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of unrealized gain (loss) on equity securities for ASU 2016-01	$ 0			$ 2,604	$ (2,604)