Earnings Per Share (Details 1) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Participating Securities, Distributed and Undistributed Earnings (Loss), Basic	$ 217		$ 319		$ 421	$ 637
Participating Securities, Distributed and Undistributed Earnings of Net Income, Percent	0.70%		0.64%		0.64%	0.59%
Earnings per share – Basic:
Net income	$ 31,112	$ 34,810	$ 50,203	$ 57,547	$ 65,922	$ 107,750
Earnings available to common shareholders – Basic	$ 30,895		$ 49,884		$ 65,501	$ 107,113
Weighted-average common shares outstanding – Basic	74,650,357		77,910,513		74,676,926	78,137,290
Earnings per common share – Basic	$ 0.41		$ 0.64		$ 0.88	$ 1.37
Earnings per share – Diluted:
Net income	$ 31,112	$ 34,810	$ 50,203	$ 57,547	$ 65,922	$ 107,750
Earnings available to common shareholders – Diluted	$ 30,895		$ 49,884		$ 65,501	$ 107,113
Weighted-average common shares outstanding – Basic	74,650,357		77,910,513		74,676,926	78,137,290
Effect of dilutive shares(2)	791,189		337,716		680,507	282,868
Weighted-average common shares outstanding – Diluted	75,441,546		78,248,229		75,357,433	78,420,158
Earnings per common share – Diluted	$ 0.41		$ 0.64		$ 0.87	$ 1.37