EPS Calculation (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Basic Earnings/(Loss) per Share:
Net (loss)/income	$ 45,817	$ 87,210	$ 96,578	$ (908,995)	$ 100,621	$ 95,599	$ 93,040	$ 88,857	$ (679,390)	$ 378,117	$ 301,801
Dividends declared on preferred stock									(29,796)	(15,000)	(15,000)
Dividends, dividend equivalents and undistributed earnings allocated to participating securities									(229)	(1,087)	(943)
Net income available to common stock and participating securities	$ 37,599	$ 78,991	$ 88,434	$ (914,210)	96,871	91,849	89,290	85,107	$ (709,415)	$ 362,030	$ 285,858
Basic weighted average common shares outstanding (in shares)									452,033	450,972	418,934
Basic Earnings/(Loss) per Common Share (usd per share)	$ 0.08	$ 0.17	$ 0.19	$ (2.02)					$ (1.57)	$ 0.80	$ 0.68
Diluted Earnings/(Loss) per Share:
Net income/(loss) to common stockholders - basic	$ 37,599	$ 78,991	$ 88,434	$ (914,210)	$ 96,871	$ 91,849	$ 89,290	$ 85,107	$ (709,415)	$ 362,030	$ 285,858
Interest expense on Convertible Senior Notes									0	8,965	0
Net income/(loss) to common stockholders - diluted									$ (709,415)	$ 370,995	$ 285,858
Basic weighted average common shares outstanding (in shares)									452,033	450,972	418,934
Effect of assumed Convertible Senior Notes conversion to common shares (in shares)									0	16,797	0
Diluted weighted average common shares outstanding (in shares)									452,033	467,769	418,934
Diluted Earnings/(Loss) per Common Share (in usd per share)	$ 0.08	$ 0.17	$ 0.19	$ (2.02)					$ (1.57)	$ 0.79	$ 0.68
Anti-dilutive securities excluded from diluted earnings per share calculations (in shares)									2,300
Restricted Stock Units
Diluted Earnings/(Loss) per Share:
Weighted average grant date fair value (in dollars per share)	$ 6.56								$ 6.56