Earnings per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net Income (Loss) Attributable to Parent									$ 188,643	$ 74,835	$ 200,352
Numerator:
Net income attributable to common shareholders	$ 20,987	$ 67,696	$ 57,435	$ 17,410	$ 638	$ 1,821	$ 42,246	$ 21,758	163,528	66,463	200,352
Preferred Stock Dividends, Income Statement Impact									(25,115)	(8,372)	0
Less: Dividends paid on unvested restricted shares									(1,181)	(1,029)	(1,105)
Less: Undistributed earnings attributable to unvested restricted shares									0	0	(188)
Net income attributable to common shareholders excluding amounts attributable to unvested restricted shares									$ 162,347	$ 65,434	$ 199,059
Denominator:
Weighted-average number of common shares - basic (in shares)	174,141,263	174,326,198	174,238,854	174,193,671	174,147,522	140,249,961	123,785,735	123,734,173	174,225,130	140,616,838	123,651,003
Unvested restricted shares (in shares)									91,275	77,211	228,004
Weighted-average number of common shares - diluted (in shares)	174,194,141	174,479,341	174,364,547	174,268,815	174,210,578	140,307,269	123,871,762	123,841,400	174,316,405	140,694,049	123,879,007
Net income per share attributable to common shareholders - basic (in dollars per share)	$ 0.12	$ 0.39	$ 0.33	$ 0.10	$ 0.00	$ 0.01	$ 0.34	$ 0.17	$ 0.93	$ 0.47	$ 1.61
Net income per share attributable to common shareholders - diluted (in dollars per share)	$ 0.12	$ 0.39	$ 0.33	$ 0.10	$ 0.00	$ 0.01	$ 0.34	$ 0.17	$ 0.93	$ 0.47	$ 1.61