Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Numerator:
Net income	$ 21,055	$ 21,552	$ 18,935	$ 19,325	$ 20,662	$ (10,054)	$ 19,698	$ 16,053	$ 80,867	$ 46,359	$ 57,923
Less: Net income allocated to participating securities									(298)	(296)	(364)
Numerator for basic and diluted earnings available to common stockholders									$ 80,569	$ 46,063	$ 57,559
Denominator:
Weighted-average basic common shares outstanding (shares)	95,215	95,214	95,208	95,161	95,103	95,103	94,036	88,010	95,200	93,088	79,386
Dilutive performance stock awards (shares)									7	10	6
Weighted-average diluted common shares outstanding (shares)	95,244	95,214	95,208	95,161	95,144	95,103	94,036	88,010	95,207	93,098	79,392
Earnings per common share, basic (usd per share)	$ 0.22	$ 0.23	$ 0.20	$ 0.20	$ 0.22	$ (0.11)	$ 0.21	$ 0.18	$ 0.85	$ 0.49	$ 0.73
Earnings per common share, diluted (usd per share)	$ 0.22	$ 0.23	$ 0.20	$ 0.20	$ 0.22	$ (0.11)	$ 0.21	$ 0.18	$ 0.85	$ 0.49	$ 0.72