Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended						9 Months Ended
	Jan. 15, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Earnings Per Share [Abstract]
Class of Warrant or Right, Date from which Warrants or Rights Exercisable	Jan. 15, 2021
Anti-dilutive securities excluded from earnings per share		0			158			5,200	450
Earnings Per Share Reconciliation [Abstract]
Net income (loss)		$ 85,593	$ (222,995)	$ (251,269)	$ (98,292)	$ (89,252)	$ (411,895)	$ (388,671)	$ (599,439)
Basic weighted-average common shares outstanding		121,457			114,371			118,224	113,462
Dilutive effect of non-vested RSUs and contingent PSUs		2,375			0			0	0
Dilutive effect of warrants		19			0			0	0
Diluted weighted-average common shares outstanding		123,851			114,371			118,224	113,462
Basic net income (loss) per common share		$ 0.70			$ (0.86)			$ (3.29)	$ (5.28)
Diluted net income (loss) per common share		$ 0.69			$ (0.86)			$ (3.29)	$ (5.28)