Comprehensive Income (Loss) per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Comprehensive Income (Loss)									$ 149,438	$ (129,725)	$ 190,177
Less: Preferred dividends	$ (3,691)	$ (3,410)	$ (4,274)	$ (4,259)	$ (4,261)	$ (4,259)	$ (4,259)	$ (4,253)	(15,634)	(17,032)	(15,880)
Comprehensive Income (Loss) available (related) to common stockholders									$ 133,804	$ (146,757)	$ 174,297
Net Comprehensive Income (Loss) per share available (related) to common stockholders:
Basic (in dollars per share)									$ 2.31	$ (3.48)	$ 4.45
Diluted (in dollars per share)									$ 2.30	$ (3.48)	$ 4.40
Weighted average common shares outstanding:
Basic (in shares)	58,902	59,077	59,654	53,630	42,656	42,047	41,912	41,887	57,833	42,128	39,170
Add: Effect of dilutive non-vested awards, assumed vested (in shares)									247
Add: Effect of dilutive non-vested awards, assumed vested (in shares)									0	0	472
Weighted average common shares outstanding - diluted (in shares)									58,080
Weighted average common shares outstanding – diluted (in shares)	59,149	59,077	59,654	53,630	42,656	42,435	42,328	42,331	57,833	42,128	39,642