Earnings Per Share (Earnings Allocable to Common Shares) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($) trading_day $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares
Numerator for basic earnings per share:
Net income (loss) allocable to common shareholders \| $	$ (65,937)	$ 291,547	$ (64,757)
Numerator for diluted earnings per share:
Net income (loss) allocable to common shareholders \| $	$ (65,937)	$ 300,547	$ (64,757)
Denominator for basic and diluted earnings per share:
Weighted average common shares outstanding for basic earnings per common share (in shares)	75,684,000	64,696,000	67,958,000
Add: Effect of assumed shares issued under treasury stock method for restricted stock units (in shares)	0	146,000	0
Add: Effect of series J convertible perpetual preferred stock (in shares)	0	15,824,000	0
Weighted average common shares outstanding for diluted earnings per common share (in shares)	75,684,000	80,666,000	67,958,000
Basic earnings per common share:
Net income (loss) allocable to common shareholders (in dollars per share) \| $ / shares	$ (0.87)	$ 4.51	$ (0.95)
Diluted earnings per common share:
Net income (loss) allocable to common shareholders (in dollars per share) \| $ / shares	$ (0.87)	$ 3.73	$ (0.95)
Anti-dilutive shares			15,704,000
3.125% senior convertible notes
Diluted earnings per common share:
Stated interest rate	3.125%
Threshold consecutive trading days \| trading_day	40
Shares issued upon conversion	0

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Period Type:	duration

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.