CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Accumulated other comprehensive income (loss) [Member]	Total
Balance at beginning of period at Dec. 31, 2019	$ 756	$ 1,280,760	$ (889,066)	$ 4,890	$ 397,340
Balance (in shares) at Dec. 31, 2019	75,619
Net income			300,438		300,438
Total other comprehensive loss				(30,646)	(30,646)
Issuance of common stock under employee benefit plans, net of forfeitures and shares withheld to cover taxes		4,104			4,104
Issuance of common stock under employee benefit plans, net of forfeitures and shares withheld to cover taxes, shares	12
Net issuance of common stock upon exercise of stock options	$ 1	6,135			6,136
Net issuance of common stock upon exercise of stock options, shares	52
Share-based compensation		5,524			5,524
Share repurchases, including fees	$ (15)	(25,273)	(548,764)		$ (574,052)
Share repurchases, including fees, shares	(1,484)				(1,484,000)
Balance at end of period at Mar. 31, 2020	$ 742	1,271,250	(1,137,392)	(25,756)	$ 108,844
Balance (in shares) at Mar. 31, 2020	74,199
Balance at beginning of period at Dec. 31, 2020	$ 711	1,280,841	(1,139,139)	(2,155)	$ 140,258	[1]
Balance (in shares) at Dec. 31, 2020	71,123				71,123,109
Net income			501,609		$ 501,609
Total other comprehensive loss				(4,143)	(4,143)
Issuance of common stock under employee benefit plans, net of forfeitures and shares withheld to cover taxes		4,090			4,090
Issuance of common stock under employee benefit plans, net of forfeitures and shares withheld to cover taxes, shares	11
Net issuance of common stock upon exercise of stock options	$ 1	9,844			9,845
Net issuance of common stock upon exercise of stock options, shares	76
Share-based compensation		5,912			5,912
Share repurchases, including fees	$ (15)	(26,654)	(637,879)		$ (664,548)
Share repurchases, including fees, shares	(1,475)				(1,475,000)
Balance at end of period at Mar. 31, 2021	$ 697	$ 1,274,033	$ (1,275,409)	$ (6,298)	$ (6,977)
Balance (in shares) at Mar. 31, 2021	69,735				69,734,990

[1] The balance sheet at December 31, 2020, has been derived from the audited consolidated financial statements at that date but does not include all of the information and footnotes required by United States generally accepted accounting principles for complete financial statements.