CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (loss)	Accumulated Deficit	Treasury Stock	Noncontrolling Interest	Total
Balance at Dec. 31, 2017	$ 1,019	$ 1,258,151	$ (18)	$ (1,498,748)	$ (3,263)	$ 152	$ (242,707)
Balance (in shares) at Dec. 31, 2017	102,046				(150)
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	$ 0	0	0	0	$ 0	(90)	(90)
Exercise of stock options, and issuance of common stock units and stock awards, net of cancellation of stock awards and repurchase of shares to satisfy tax withholding	$ (5)	(2,492)	0	0	0	0	(2,497)
Exercise of stock options, and issuance of common stock units and stock awards, net of cancellation of stock awards and repurchase of shares to satisfy tax withholding (in shares)	(571)
Stock-based compensation	$ 0	2,169	0	0	0	0	2,169
Cash dividend forfeited	0	52	0	0	0	0	52
Net income	0	0	0	29,581	0	749	30,330
Other comprehensive income (loss)	0	0	(4)	0	0	0	(4)
Balance at Mar. 31, 2018	$ 1,014	1,257,880	(22)	(1,469,167)	$ (3,263)	811	(212,747)
Balance (in shares) at Mar. 31, 2018	101,475				(150)
Balance at Dec. 31, 2017	$ 1,019	1,258,151	(18)	(1,498,748)	$ (3,263)	152	(242,707)
Balance (in shares) at Dec. 31, 2017	102,046				(150)
Increase (Decrease) in Stockholders' Equity
Net income							86,946
Balance at Jun. 30, 2018	$ 1,015	1,259,443	(10)	(1,414,541)	$ (3,263)	1,992	(155,364)
Balance (in shares) at Jun. 30, 2018	101,657				(150)
Balance at Mar. 31, 2018	$ 1,014	1,257,880	(22)	(1,469,167)	$ (3,263)	811	(212,747)
Balance (in shares) at Mar. 31, 2018	101,475				(150)
Increase (Decrease) in Stockholders' Equity
Distributions to noncontrolling interest	$ 0	0	0	0	$ 0	(809)	(809)
Exercise of stock options, and issuance of common stock units and stock awards, net of cancellation of stock awards and repurchase of shares to satisfy tax withholding	$ 1	110	0	0	0	0	111
Exercise of stock options, and issuance of common stock units and stock awards, net of cancellation of stock awards and repurchase of shares to satisfy tax withholding (in shares)	182
Stock-based compensation	$ 0	1,452	0	0	0	0	1,452
Cash dividend forfeited	0	1	0	0	0	0	1
Net income	0	0	0	54,626	0	1,990	56,616
Other comprehensive income (loss)	0	0	12	0	0	0	12
Balance at Jun. 30, 2018	$ 1,015	1,259,443	(10)	(1,414,541)	$ (3,263)	1,992	(155,364)
Balance (in shares) at Jun. 30, 2018	101,657				(150)
Balance at Dec. 31, 2018	$ 1,011	1,256,267	(3)	(1,103,692)		5,469	$ 159,052	[1]
Balance (in shares) at Dec. 31, 2018	101,098						101,098
Increase (Decrease) in Stockholders' Equity
Exercise of stock options, and issuance of common stock units and stock awards, net of cancellation of stock awards and repurchase of shares to satisfy tax withholding	$ 1	253	0	0		0	$ 254
Exercise of stock options, and issuance of common stock units and stock awards, net of cancellation of stock awards and repurchase of shares to satisfy tax withholding (in shares)	85
Stock-based compensation	$ 0	605	0	0		0	605
Net income	0	0	0	33,790		6,229	40,019
Other comprehensive income (loss)	0	0	13	0		0	13
Balance at Mar. 31, 2019	$ 1,012	1,257,125	10	(1,069,902)		11,698	199,943
Balance (in shares) at Mar. 31, 2019	101,183
Balance at Dec. 31, 2018	$ 1,011	1,256,267	(3)	(1,103,692)		5,469	$ 159,052	[1]
Balance (in shares) at Dec. 31, 2018	101,098						101,098
Increase (Decrease) in Stockholders' Equity
Net income							$ 86,080
Balance at Jun. 30, 2019	$ 1,013	1,257,799	33	(1,032,162)		20,019	$ 246,702
Balance (in shares) at Jun. 30, 2019	101,272						101,272
Balance at Mar. 31, 2019	$ 1,012	1,257,125	10	(1,069,902)		11,698	$ 199,943
Balance (in shares) at Mar. 31, 2019	101,183
Increase (Decrease) in Stockholders' Equity
Exercise of stock options, and issuance of common stock units and stock awards, net of cancellation of stock awards and repurchase of shares to satisfy tax withholding	$ 1	200	0	0		0	201
Exercise of stock options, and issuance of common stock units and stock awards, net of cancellation of stock awards and repurchase of shares to satisfy tax withholding (in shares)	89
Stock-based compensation	$ 0	474	0	0		0	474
Net income	0	0	0	37,740		8,321	46,061
Other comprehensive income (loss)	0	0	23	0		0	23
Balance at Jun. 30, 2019	$ 1,013	$ 1,257,799	$ 33	$ (1,032,162)		$ 20,019	$ 246,702
Balance (in shares) at Jun. 30, 2019	101,272						101,272

[1] Condensed consolidated balance sheet as of December 31, 2018 has been derived from audited consolidated financial statements.