Earnings Per Share (Details) - USD ($) $ / shares in Units, $ 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
Numerator:
Net income (loss) attributable to common shareholders	$ 11,404	$ 21,752	$ 52,234	$ (2,504)	$ (104,307)	$ 25,769	$ 54,079	$ 20,386	$ 82,886	$ (4,073)	$ 83,794
Less: dividends paid on unvested share-based compensation									(294)	(332)	(415)
Net income (loss) available to common shareholders									$ 82,592	$ (4,405)	$ 83,379
Denominator:
Weighted-average number of common shares — basic (in shares)									130,471,670	74,286,307	69,591,973
Effect of dilutive share-based compensation (in shares)									246,636	0	392,864
Weighted-average number of common shares — diluted (in shares)									130,718,306	74,286,307	69,984,837
Net income (loss) per share available to common shareholders — basic (in usd per share)	$ 0.08	$ 0.17	$ 0.40	$ (0.02)	$ (1.16)	$ 0.37	$ 0.78	$ 0.29	$ 0.63	$ (0.06)	$ 1.20
Net income (loss) per share available to common shareholders — diluted (in usd per share)	$ 0.08	$ 0.17	$ 0.40	$ (0.02)	$ (1.16)	$ 0.37	$ 0.78	$ 0.29	$ 0.63	$ (0.06)	$ 1.19
Antidilutive securities excluded from computation of earnings per share (in shares)									0	343,941	6,319