Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net income	$ 57,116	$ 88,082	$ 6,113	$ 247,595
Preferred stock dividends	2,438	2,438	7,313	7,313
Net income/(loss) available to common stockholders	$ 54,678	$ 85,644	$ (1,200)	$ 240,282
Denominator:
Basic earnings per share - weighted average shares	50,446,691	50,305,844	50,417,563	50,273,485
Effect of employee stock-based awards	126,382	110,558	103,984	119,277
Denominator for dilutive earnings per share—adjusted weighted average shares and assumed conversions	50,573,073	50,416,402	50,521,547	50,392,762
Basic earnings/(loss) per common share	$ 1.08	$ 1.70	$ (0.02)	$ 4.78
Diluted earnings/(loss) per common share	$ 1.08	$ 1.70	$ (0.02)	$ 4.77
Stock options excluded from computation of EPS	480,062	107,615