CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning Balance at Dec. 31, 2019	$ 2,833,620	$ 2,694	$ 2,875,680	$ 1,294,902	$ 5,478	$ (1,345,134)
Beginning Balance (in shares) at Dec. 31, 2019		269,372,000
Net loss	(434,722)			(434,722)
Foreign currency translation adjustment	(1,386)				(1,386)
Vesting of restricted stock units		$ 1	(1)
Vesting of restricted stock units (in shares)		151,000
Stock-based compensation	9,160		9,160
Payment of cash dividends	(7,629)			(7,629)
Dividend equivalents	(125)			(125)
Purchase of treasury stock	(20,025)					(20,025)
Ending Balance at Mar. 31, 2020	2,378,893	$ 2,695	2,884,839	852,426	4,092	(1,365,159)
Ending Balance (in shares) at Mar. 31, 2020		269,523,000
Beginning Balance at Dec. 31, 2019	2,833,620	$ 2,694	2,875,680	1,294,902	5,478	(1,345,134)
Beginning Balance (in shares) at Dec. 31, 2019		269,372,000
Net loss	(585,054)
Foreign currency translation adjustment	(691)
Ending Balance at Jun. 30, 2020	2,228,873	$ 2,706	2,889,163	698,286	4,787	(1,366,069)
Ending Balance (in shares) at Jun. 30, 2020		270,569,000
Beginning Balance at Mar. 31, 2020	2,378,893	$ 2,695	2,884,839	852,426	4,092	(1,365,159)
Beginning Balance (in shares) at Mar. 31, 2020		269,523,000
Net loss	(150,332)			(150,332)
Foreign currency translation adjustment	695				695
Vesting of restricted stock units		$ 11	(11)
Vesting of restricted stock units (in shares)		1,046,000
Stock-based compensation	4,335		4,335
Payment of cash dividends	(3,735)			(3,735)
Dividend equivalents	(73)			(73)
Purchase of treasury stock	(910)					(910)
Ending Balance at Jun. 30, 2020	2,228,873	$ 2,706	2,889,163	698,286	4,787	(1,366,069)
Ending Balance (in shares) at Jun. 30, 2020		270,569,000
Beginning Balance at Dec. 31, 2020	$ 2,016,059	$ 2,710	2,902,236	472,014	5,412	(1,366,313)
Beginning Balance (in shares) at Dec. 31, 2020	271,028,688	271,029,000
Net loss	$ (106,413)			(106,413)
Foreign currency translation adjustment	418				418
Vesting of restricted stock units		$ 2	(2)
Vesting of restricted stock units (in shares)		163,000
Stock-based compensation	5,891		5,891
Payment of cash dividends	(3,754)			(3,754)
Dividend equivalents	(55)			(55)
Ending Balance at Mar. 31, 2021	1,912,146	$ 2,712	2,908,125	361,792	5,830	(1,366,313)
Ending Balance (in shares) at Mar. 31, 2021		271,192,000
Beginning Balance at Dec. 31, 2020	$ 2,016,059	$ 2,710	2,902,236	472,014	5,412	(1,366,313)
Beginning Balance (in shares) at Dec. 31, 2020	271,028,688	271,029,000
Net loss	$ (209,722)
Foreign currency translation adjustment	673
Ending Balance at Jun. 30, 2021	$ 1,807,717	$ 2,728	2,914,043	254,696	6,085	(1,369,835)
Ending Balance (in shares) at Jun. 30, 2021	272,835,137	272,835,000
Beginning Balance at Mar. 31, 2021	$ 1,912,146	$ 2,712	2,908,125	361,792	5,830	(1,366,313)
Beginning Balance (in shares) at Mar. 31, 2021		271,192,000
Net loss	(103,309)			(103,309)
Foreign currency translation adjustment	255				255
Vesting of restricted stock units		$ 16	(16)
Vesting of restricted stock units (in shares)		1,643,000
Stock-based compensation	5,934		5,934
Payment of cash dividends	(3,769)			(3,769)
Dividend equivalents	(18)			(18)
Purchase of treasury stock	(3,522)					(3,522)
Ending Balance at Jun. 30, 2021	$ 1,807,717	$ 2,728	$ 2,914,043	$ 254,696	$ 6,085	$ (1,369,835)
Ending Balance (in shares) at Jun. 30, 2021	272,835,137	272,835,000