Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Anti-dilutive securities excluded from earnings per share	1,219	781
Calculation of basic and diluted earnings per share
Net loss	$ (411,895)	$ (177,568)
Basic weighted-average common shares outstanding	113,009	112,252
Dilutive effect of non-vested RSUs and contingent PSUs	0	0
Diluted weighted-average common shares outstanding	113,009	112,252
Basic net loss per common share	$ (3.64)	$ (1.58)
Diluted net loss per common share	(3.64)	(1.58)
1.50% Senior Convertible Notes Due 2021 [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Senior Convertible Notes, conversion price	$ 40.50	$ 40.50