Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock
Opening Balance, at Dec. 31, 2015	$ 352,880	$ 5,173	$ 30,739	$ 304,340	$ 13,002	$ (374)
Opening Balance (in shares) at Dec. 31, 2015		5,173,000
Net income	22,019			22,019
Dividends paid	(20,452)			(20,452)
Change in unrealized net gain on available-for-sale securities	(777)				(777)
Change in value of interest rate cap	16				16
Closing Balance (in shares) at Mar. 31, 2016		5,173,000
Closing Balance, at Mar. 31, 2016	353,686	$ 5,173	30,739	305,907	12,241	(374)
Opening Balance, at Dec. 31, 2016	$ 352,845	$ 5,173	31,189	308,995	7,862	(374)
Opening Balance (in shares) at Dec. 31, 2016	5,173,450	5,173,000
Net income	$ 21,667			21,667
Dividends paid	(21,737)			(21,737)
Change in unrealized net gain on available-for-sale securities	(3,447)				(3,447)
Change in value of interest rate cap	56				56
Other	$ 0		(6)			6
Closing Balance (in shares) at Mar. 31, 2017	5,173,450	5,173,000
Closing Balance, at Mar. 31, 2017	$ 349,384	$ 5,173	$ 31,183	$ 308,925	$ 4,471	$ (368)