Basis of Presentation (Reconciliation of Net Income (Loss) and Weighted Average Shares Table) (Details) - USD ($) shares in Thousands, $ in Thousands		3 Months Ended
	Sep. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Sep. 18, 2020	Jun. 30, 2020	Mar. 31, 2020
Numerator
Net income (loss) - basic	$ 2,758	$ (69,642)	$ (53,416)	$ (809,120)	$ (697,474)	$ 74,016
Interest on convertible senior notes including amortization of discount, net of tax		0				5,857
Net income (loss) - diluted		$ (69,642)				$ 79,873
Denominator
Weighted average common shares outstanding - basic		50,319				494,259
Restricted stock and performance-based equity awards		0				1,078
Convertible senior notes		0				90,853	[1]
Weighted average common shares outstanding - diluted		50,319				586,190

[1] In connection with the Company’s emergence from bankruptcy on September 18, 2020, all outstanding convertible senior notes were fully extinguished.