Consolidated Statement of Changes in Equity (USD $) In Thousands, except Share data	Total	Common Stock	Additional Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock	Non-controlling Interest
Opening Balance, at Dec. 31, 2011	$ 363,245	$ 5,173	$ 31,801	$ 322,201	$ 0	$ (375)	$ 4,445
Shares Issued, Beginning Balance (in shares) at Dec. 31, 2011		5,173,000
Net income	674,993			674,387			606
Dividends paid	(699,791)			(699,791)
Acquisition of the noncontrolling interest	(7,800)		(2,749)				(5,051)
Change in unrealized net gain on available-for-sale securities	1,206				1,206
Deferred stock unit grant	300		300
Closing Balance, at Dec. 31, 2012	332,153	5,173	29,352	296,797	1,206	(375)	0
Shares Issued, Ending Balance (in shares) at Dec. 31, 2012		5,173,000
Net income	56,915			56,915			0
Dividends paid	(56,197)			(56,197)
Change in unrealized net gain on available-for-sale securities	316				316
Deferred stock unit grant	394		394
Other	0		(1)			1
Balance, at Dec. 31, 2013	333,581	5,173	29,745	297,515	1,522	(374)	0
Shares Issued, Ending Balance (in shares) at Dec. 31, 2013	5,173,450	5,173,000
Net income	67,925			67,925			0
Dividends paid	(66,436)			(66,436)
Change in unrealized net gain on available-for-sale securities	13,124				13,124
Change in value of interest rate cap	(189)				(189)
Deferred stock unit grant	394		394
Balance, at Dec. 31, 2014	$ 348,399	$ 5,173	$ 30,139	$ 299,004	$ 14,457	$ (374)	$ 0
Shares Issued, Ending Balance (in shares) at Dec. 31, 2014	5,173,450	5,173,000