Net Income (Loss) per Share - Basic and Diluted Net Income per Share of Common Stock Using Two-Class Method (Details) - USD ($) $ / shares in Units, $ 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
Net income	$ 36,680	$ 49,338	$ 60,201	$ (127,842)	$ 71,903	$ 29,089	$ 61,424	$ 67,758	$ 18,377	$ 230,174	$ 219,986
Less: Preferred dividends	(3,385)	(3,385)	(3,385)	(3,385)	(3,386)	(3,385)	(4,919)	(6,835)	(13,540)	(18,525)	(27,340)
Net income available to common stockholders	$ 33,295	$ 45,953	$ 56,816	$ (131,227)	$ 68,517	$ 25,704	$ 56,505	$ 60,923	4,837	211,649	192,646
Less: Dividends on participating securities									(3,431)	(3,867)	(3,405)
Basic Earnings									1,406	207,782	189,241
Diluted Earnings
Net income available to common stockholders									4,837	211,649	192,646
Less: Dividends on participating securities									(3,431)	0	0
Add: Interest expense on Notes									0	35,173	34,779
Diluted Earnings									$ 1,406	$ 246,822	$ 227,425
Number of Shares:
Basic weighted-average shares of common stock outstanding (in shares)	140,036,383	146,612,313	151,523,513	153,948,191	153,537,074	153,531,678	145,567,963	134,607,107	148,004,385	146,881,231	124,147,073
Diluted weighted-average shares of common stock outstanding (in shares)	140,036,383	146,612,313	182,083,702	153,948,191	182,070,345	153,531,678	174,101,234	164,683,086	148,004,385	175,794,896	153,821,515
Earnings Per Share Attributable to Common Stockholders
Basic (in dollars per share)	$ 0.23	$ 0.31	$ 0.37	$ (0.86)	$ 0.44	$ 0.16	$ 0.38	$ 0.45	$ 0.01	$ 1.41	$ 1.52
Diluted (in dollars per share)	$ 0.23	$ 0.31	$ 0.36	$ (0.86)	$ 0.42	$ 0.16	$ 0.37	$ 0.43	$ 0.01	$ 1.40	$ 1.48