Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Treasury Stock, Shares			(790,000)
Common stock, shares, outstanding at Dec. 31, 2018		79,004,000
Beginning Balance, value at Dec. 31, 2018	$ 165,058	$ 7,900	$ (4,965)	$ 550,548	$ (388,425)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net loss	(15,115)				(15,115)
Purchase of treasury stock, shares			(84,000)
Purchase of treasury stock, value	(120)		$ (120)
Equity awards vested or exercised, shares		326,000
Equity awards vested or exercised, value		$ 33		(33)
Stock-based compensation expense	867			867
Common stock, shares, outstanding at Mar. 31, 2019		79,330,000
Ending Balance, value at Mar. 31, 2019	150,967	$ 7,933	(5,085)	551,382	(403,263)
Common stock, shares, outstanding at Dec. 31, 2018		79,004,000
Beginning Balance, value at Dec. 31, 2018	165,058	$ 7,900	(4,965)	550,548	(388,425)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net loss	(28,059)
Common stock, shares, outstanding at Jun. 30, 2019		79,997,000
Ending Balance, value at Jun. 30, 2019	138,345	$ 8,000	$ (5,090)	551,642	(416,207)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Treasury Stock, Shares			(874,000)
Cumulative-effect adjustment due to adoption of ASC Topic 842 | Accounting Standards Update 2016-02 [Member]	277				277
Common stock, shares, outstanding at Mar. 31, 2019		79,330,000
Beginning Balance, value at Mar. 31, 2019	150,967	$ 7,933	$ (5,085)	551,382	(403,263)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net loss	(12,944)				(12,944)
Purchase of treasury stock, shares			(3,000)
Purchase of treasury stock, value	(5)		$ (5)
Equity awards vested or exercised, shares		667,000
Equity awards vested or exercised, value		$ 67		(67)
Stock-based compensation expense	327			327
Common stock, shares, outstanding at Jun. 30, 2019		79,997,000
Ending Balance, value at Jun. 30, 2019	138,345	$ 8,000	$ (5,090)	551,642	(416,207)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Treasury Stock, Shares			(877,000)
Treasury Stock, Shares			(877,000)
Common stock, shares, outstanding at Dec. 31, 2019		80,079,000
Beginning Balance, value at Dec. 31, 2019	104,076	$ 8,008	$ (5,090)	553,210	(452,052)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net loss	(69,104)				(69,104)
Purchase of treasury stock, shares			(165,000)
Purchase of treasury stock, value	(7)		$ (7)
Equity awards vested or exercised, shares		542,000
Equity awards vested or exercised, value		$ 54		(54)
Stock-based compensation expense	328			328
Common stock, shares, outstanding at Mar. 31, 2020		80,621,000
Ending Balance, value at Mar. 31, 2020	35,293	$ 8,062	(5,097)	553,484	(521,156)
Common stock, shares, outstanding at Dec. 31, 2019		80,079,000
Beginning Balance, value at Dec. 31, 2019	104,076	$ 8,008	(5,090)	553,210	(452,052)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net loss	(104,225)
Common stock, shares, outstanding at May. 31, 2020		0
Ending Balance, value at May. 31, 2020	0	$ 0	$ 0	0	0
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Treasury Stock, Shares			(1,042,000)
Common stock, shares, outstanding at Mar. 31, 2020		80,621,000
Beginning Balance, value at Mar. 31, 2020	35,293	$ 8,062	$ (5,097)	553,484	(521,156)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Net loss	(35,121)
Purchase of treasury stock, shares			(100,000)
Purchase of treasury stock, value	(1)		$ (1)
Equity awards vested or exercised, shares		363,000
Equity awards vested or exercised, value		$ 36		(36)
Equity awards vested in connection with the Plan, shares		7,946,000
Equity awards vested in connection with the Plan, value		$ 795		(795)
Stock-based compensation expense	978			978
Common stock, shares, outstanding at May. 31, 2020		0
Ending Balance, value at May. 31, 2020	0	$ 0	$ 0	0	0
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Treasury Stock, Shares			0
Net loss	$ (9,817)
Purchase of treasury stock, shares			(1,000)
Common stock, shares, outstanding at Jun. 30, 2020	1,048,185	1,050,000
Ending Balance, value at Jun. 30, 2020	$ 129,142	$ 1	$ 0	138,958	$ (9,817)
Increase (Decrease) in Shareholders' Equity [Roll Forward]
Stock Issued During Period, Shares, New Issues		1,050,000
Stock Issued During Period, Value, New Issues	18,084	$ 1
Equity component of Convertible Notes, net of offering costs	$ 120,875			$ 120,875
Treasury Stock, Shares			(1,000)