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, 2015	$ 1,149	$ 1,351,898	$ (2)	$ (1,692,427)	$ (3,263)	$ 0	$ (342,645)
Balance (in shares) at Dec. 31, 2015	114,933				(150)
Increase (Decrease) in Stockholders' Equity
Exercise of stock options, and issuance of common stock units and stock awards	$ 8	(674)	0	0	$ 0	0	(666)
Exercise of stock options, and issuance of common stock units and stock awards (in shares)	853				0
Partial termination of capped call options associated with repurchases of convertible notes due 2023	$ 0	578	0	0	$ 0	0	578
Stock-based compensation	0	8,297	0	0	0	0	8,297
Repurchase of common stock	$ (72)	(78,022)	0	0	$ 0	0	(78,094)
Repurchase of common stock (in shares)	(7,201)				0
Net income	$ 0	0	0	59,536	$ 0	0	59,536
Other comprehensive income (loss)	0	0	3	0	0	0	3
Balance at Dec. 31, 2016	$ 1,085	1,282,077	1	(1,632,891)	$ (3,263)	0	(352,991)
Balance (in shares) at Dec. 31, 2016	108,585				(150)
Increase (Decrease) in Stockholders' Equity
Contributions from noncontrolling interest	$ 0	0	0	0	$ 0	23	23
Exercise of stock options, and issuance of common stock units and stock awards	$ 9	(1,702)	0	0	$ 0	0	(1,693)
Exercise of stock options, and issuance of common stock units and stock awards (in shares)	891				0
Stock-based compensation	$ 0	9,833	0	0	$ 0	0	9,833
Cash dividend forfeited	0	7	0	0	0	0	7
Repurchase of common stock	$ (75)	(97,425)	0	0	$ 0	0	(97,500)
Repurchase of common stock (in shares)	(7,430)				0
Equity components of Convertible Senior Notes due 2025, net of issuance costs	$ 0	65,361	0	0	$ 0	0	65,361
Net income	0	0	0	134,143	0	129	134,272
Other comprehensive income (loss)	0	0	(19)	0	0	0	(19)
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	(5,955)	(5,955)
Exercise of stock options, and issuance of common stock units and stock awards	$ (8)	(1,926)	0	0	$ 0	0	(1,934)
Exercise of stock options, and issuance of common stock units and stock awards (in shares)	(798)				0
Stock-based compensation	$ 0	3,233	0	0	$ 0	0	3,233
Cash dividend forfeited	0	72	0	0	0	0	72
Net income	0	0	0	395,056	0	11,272	406,328
Other comprehensive income (loss)	0	0	15	0	0	0	15
Retirement of treasury stock	$ 0	(3,263)	0	0	$ 3,263	0	0
Retirement of treasury stock (in shares)	(150)				150
Balance at Dec. 31, 2018	$ 1,011	$ 1,256,267	$ (3)	$ (1,103,692)	$ 0	$ 5,469	$ 159,052
Balance (in shares) at Dec. 31, 2018	101,098				0		101,098