Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Shares	Capital in Excess of Par Value	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2019		176,505
Beginning balance at Dec. 31, 2019	$ 1,405,391	$ 17	$ 3,271,097	$ (1,005)	$ (1,864,718)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under equity compensation plans (in shares)		1,358
Shares issued under equity compensation plans	11,347		11,347
Stock-based compensation	24,211		24,211
Comprehensive income (loss)	(144,523)			(5,872)	(138,651)
Ending balance (in shares) at Mar. 31, 2020		177,863
Ending balance at Mar. 31, 2020	1,296,426	$ 17	3,306,655	(6,877)	(2,003,369)
Beginning balance (in shares) at Dec. 31, 2019		176,505
Beginning balance at Dec. 31, 2019	$ 1,405,391	$ 17	3,271,097	(1,005)	(1,864,718)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under equity compensation plans (in shares)	2,305
Comprehensive income (loss)	$ (216,931)
Ending balance (in shares) at Jun. 30, 2020		178,810
Ending balance at Jun. 30, 2020	1,256,240	$ 18	3,338,876	715	(2,083,369)
Beginning balance (in shares) at Mar. 31, 2020		177,863
Beginning balance at Mar. 31, 2020	$ 1,296,426	$ 17	3,306,655	(6,877)	(2,003,369)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under equity compensation plans (in shares)	947	947
Shares issued under equity compensation plans	$ 7,826	$ 1	7,825
Stock-based compensation	24,396		24,396
Comprehensive income (loss)	(72,408)			7,592	(80,000)
Ending balance (in shares) at Jun. 30, 2020		178,810
Ending balance at Jun. 30, 2020	1,256,240	$ 18	3,338,876	715	(2,083,369)
Beginning balance (in shares) at Dec. 31, 2020		180,091
Beginning balance at Dec. 31, 2020	1,077,295	$ 18	3,388,730	(2,295)	(2,309,158)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under equity compensation plans (in shares)		2,199
Shares issued under equity compensation plans	17,106		17,106
Stock-based compensation	23,898		23,898
Comprehensive income (loss)	(123,793)			(826)	(122,967)
Ending balance (in shares) at Mar. 31, 2021		182,290
Ending balance at Mar. 31, 2021	994,506	$ 18	3,429,734	(3,121)	(2,432,125)
Beginning balance (in shares) at Dec. 31, 2020		180,091
Beginning balance at Dec. 31, 2020	$ 1,077,295	$ 18	3,388,730	(2,295)	(2,309,158)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under equity compensation plans (in shares)	3,682
Comprehensive income (loss)	$ (249,591)
Ending balance (in shares) at Jun. 30, 2021		183,773
Ending balance at Jun. 30, 2021	904,975	$ 18	3,466,001	(3,400)	(2,557,644)
Beginning balance (in shares) at Mar. 31, 2021		182,290
Beginning balance at Mar. 31, 2021	$ 994,506	$ 18	3,429,734	(3,121)	(2,432,125)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under equity compensation plans (in shares)	1,483	1,483
Shares issued under equity compensation plans	$ 12,553		12,553
Stock-based compensation	23,714		23,714
Comprehensive income (loss)	(125,798)			(279)	(125,519)
Ending balance (in shares) at Jun. 30, 2021		183,773
Ending balance at Jun. 30, 2021	$ 904,975	$ 18	$ 3,466,001	$ (3,400)	$ (2,557,644)