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, 2014	$ 348,399	$ 5,173	$ 30,139	$ 299,004	$ 14,457	$ (374)
Opening Balance (in shares) at Dec. 31, 2014		5,173,000
Net income	17,822			17,822
Dividends paid	(17,890)			(17,890)
Change in unrealized net gain on available-for-sale securities	493				493
Change in value of interest rate cap	(6)				(6)
Closing Balance (in shares) at Mar. 31, 2015		5,173,000
Closing Balance, at Mar. 31, 2015	348,818	$ 5,173	30,139	298,936	14,944	(374)
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	5,173,450	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	5,173,450	5,173,000
Closing Balance, at Mar. 31, 2016	$ 353,686	$ 5,173	$ 30,739	$ 305,907	$ 12,241	$ (374)