Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator:
Net income/(loss)	$ (34,316)	$ 77,812	$ (51,003)	$ 159,513
Preferred stock dividends	2,437	2,437	4,875	4,875
Net income/(loss) available to common stockholders	$ (36,753)	$ 75,375	$ (55,878)	$ 154,638
Denominator:
Basic earnings per share - weighted average shares	50,392,394	50,280,776	50,401,401	50,257,039
Effect of employee stock-based awards	23,937	103,094	71,749	102,954
Denominator for dilutive earnings per share—adjusted weighted average shares and assumed conversions	50,416,331	50,383,870	50,473,150	50,359,993
Basic earnings/(loss) per common share	$ (0.73)	$ 1.50	$ (1.11)	$ 3.07
Diluted earnings/(loss) per common share	$ (0.73)	$ 1.50	$ (1.11)	$ 3.07
Stock options excluded from computation of EPS	510,095	116,840