CONSOLIDATED STATEMENT OF CHANGES IN EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Accumulated Deficit	AOCI Attributable to Parent	Common Stock	Additional Paid-in Capital	Treasury Stock
Balance at Dec. 31, 2017	$ 81,796	$ (715,476)	$ (113)	$ 2,157	$ 812,536	$ (17,308)
Balance (in shares) at Dec. 31, 2017				21,573
Balance (in shares) at Dec. 31, 2017						999
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(6,170)	(6,170)
Issuance of and restricted stock withheld for taxes	(150)				(17)	$ (133)
Issuance of restricted stock, net of tax withholdings (in shares)						13
Stock-based compensation expense	277				277
Other comprehensive loss	82		82
Balance at Mar. 31, 2018	75,835	(721,646)	(31)	$ 2,157	812,796	$ (17,441)
Balance (in shares) at Mar. 31, 2018				21,573
Balance (in shares) at Mar. 31, 2018						1,012
Balance at Dec. 31, 2017	81,796	(715,476)	(113)	$ 2,157	812,536	$ (17,308)
Balance (in shares) at Dec. 31, 2017				21,573
Balance (in shares) at Dec. 31, 2017						999
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	994
Balance at Sep. 30, 2018	83,509	(714,482)	(13)	$ 2,157	811,131	$ (15,284)
Balance (in shares) at Sep. 30, 2018				21,573
Balance (in shares) at Sep. 30, 2018						926
Balance at Mar. 31, 2018	75,835	(721,646)	(31)	$ 2,157	812,796	$ (17,441)
Balance (in shares) at Mar. 31, 2018				21,573
Balance (in shares) at Mar. 31, 2018						1,012
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(24,896)	(24,896)
Issuance of and restricted stock withheld for taxes	(50)				(2,024)	$ 1,974
Issuance of restricted stock, net of tax withholdings (in shares)						88
Stock options exercised, net of tax withholdings	0				(16)	$ 16
Stock options exercised, net of tax withholdings (in shares)						(1)
Stock-based compensation expense	333				333
Other comprehensive loss	(1)		(1)
Balance at Jun. 30, 2018	51,221	(746,542)	(32)	$ 2,157	811,089	$ (15,451)
Balance (in shares) at Jun. 30, 2018				21,573
Balance (in shares) at Jun. 30, 2018						923
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	32,060	32,060
Issuance of and restricted stock withheld for taxes	(34)				(201)	$ 167
Issuance of restricted stock, net of tax withholdings (in shares)						3
Stock-based compensation expense	243				243
Other comprehensive loss	19		19
Balance at Sep. 30, 2018	83,509	(714,482)	(13)	$ 2,157	811,131	$ (15,284)
Balance (in shares) at Sep. 30, 2018				21,573
Balance (in shares) at Sep. 30, 2018						926
Balance at Dec. 31, 2018	66,979	(731,105)	0	$ 2,157	810,928	$ (15,001)
Balance (in shares) at Dec. 31, 2018				21,573
Balance (in shares) at Dec. 31, 2018						914
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	21,663	21,663
Stock options exercised, net of tax withholdings	0
Stock options exercised, net of tax withholdings (in shares)						(1)
Cancellations of and restricted stock withheld for taxes	(149)				7	$ (156)
Cancellations of and restricted stock withheld for taxes (in shares)						83
Stock-based compensation expense	417				417
Other comprehensive loss	(31)		(31)
Balance at Mar. 31, 2019	88,879	(709,442)	(31)	$ 2,157	811,352	$ (15,157)
Balance (in shares) at Mar. 31, 2019				21,573
Balance (in shares) at Mar. 31, 2019						998
Balance at Dec. 31, 2018	66,979	(731,105)	0	$ 2,157	810,928	$ (15,001)
Balance (in shares) at Dec. 31, 2018				21,573
Balance (in shares) at Dec. 31, 2018						914
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	55,259
Balance at Sep. 30, 2019	122,937	(675,846)	(25)	$ 2,157	810,649	$ (13,998)
Balance (in shares) at Sep. 30, 2019				21,573
Balance (in shares) at Sep. 30, 2019						928
Balance at Mar. 31, 2019	88,879	(709,442)	(31)	$ 2,157	811,352	$ (15,157)
Balance (in shares) at Mar. 31, 2019				21,573
Balance (in shares) at Mar. 31, 2019						998
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	36,093	36,093
Issuance of and restricted stock withheld for taxes	(31)				(1,220)	$ 1,189
Issuance of restricted stock, net of tax withholdings (in shares)						77
Stock-based compensation expense	269				269
Other comprehensive loss	6		6
Balance at Jun. 30, 2019	125,216	(673,349)	(25)	$ 2,157	810,401	$ (13,968)
Balance (in shares) at Jun. 30, 2019				21,573
Balance (in shares) at Jun. 30, 2019						921
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(2,497)	(2,497)
Issuance of and restricted stock withheld for taxes	(30)					$ (30)
Issuance of restricted stock, net of tax withholdings (in shares)						7
Stock-based compensation expense	248				248
Other comprehensive loss	0		0
Balance at Sep. 30, 2019	$ 122,937	$ (675,846)	$ (25)	$ 2,157	$ 810,649	$ (13,998)
Balance (in shares) at Sep. 30, 2019				21,573
Balance (in shares) at Sep. 30, 2019						928