Selected Quarterly Financial Data (Unaudited) - Schedule of Unaudited Quarterly Data (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
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 44,228	$ 33,314	$ 46,201	$ 39,658	$ 40,361	$ 39,510	$ 38,969	$ 38,101	$ 163,401	$ 156,941	$ 132,982
Net income (loss)	$ 20,662	$ (10,054)	$ 19,698	$ 16,053	$ 15,539	$ 14,510	$ 13,267	$ 14,607	$ 46,359	$ 57,923	$ 25,874
Earnings per common share, basic (usd per share)	$ 0.22	$ (0.11)	$ 0.21	$ 0.18	$ 0.18	$ 0.18	$ 0.17	$ 0.19	$ 0.49	$ 0.73	$ 0.35
Earnings per common share, diluted (usd per share)	$ 0.22	$ (0.11)	$ 0.21	$ 0.18	$ 0.18	$ 0.18	$ 0.17	$ 0.19	$ 0.49	$ 0.72	$ 0.35
Weighted-average number of common shares outstanding, basic (shares)	95,103	95,103	94,036	88,010	84,059	81,490	76,374	75,504	93,088	79,386	72,647
Weighted-average number of common shares outstanding, diluted (shares)	95,144	95,103	94,036	88,010	84,084	81,490	76,374	75,504	93,098	79,392	72,647