Net Income per Common 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 attributable to common stockholders and participating securities for basic and diluted earnings per share	$ 12,489	$ 19,720	$ 10,614	$ 27,876	$ (17,655)	$ 20,882	$ 1,453	$ 21,729	$ 70,699	$ 26,409	$ 85,097
Dividends and undistributed earnings allocated to participating securities									303	138	312
Net income allocable to common stockholders—basic and diluted									$ 70,396	$ 26,271	$ 84,785
Denominator:
Weighted average common shares outstanding for basic earnings per share (in shares)									51,278,932	43,388,810	41,817,455
Weighted average common shares outstanding for diluted earnings per share (in shares)									51,278,932	43,388,810	41,817,455
Basic earnings per common share (in dollars per share)	$ 0.23	$ 0.37	$ 0.21	$ 0.58	$ (0.37)	$ 0.50	$ 0.03	$ 0.52	$ 1.37	$ 0.61	$ 2.03
Diluted earnings per common share (in dollars per share)	$ 0.23	$ 0.37	$ 0.21	$ 0.58	$ (0.37)	$ 0.50	$ 0.03	$ 0.52	$ 1.37	$ 0.61	$ 2.03