Consolidated Statements of Changes in Equity (USD $) In Thousands, except Share data	Total	Common Stock [Member]	Additional Capital	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Balance, at Dec. 31, 2011	$ 363,245	$ 5,173	$ 31,801	$ 322,201		$ (375)	$ 4,445
Shares Issued, Beginning Balance at Dec. 31, 2011		5,173,000
Net income	38,662			38,374			288
Dividends paid	(38,303)			(38,303)
Change in unrealized net gain on available-for-sale securities	0
Deferred stock unit grant	300		300
Balance, at Jun. 30, 2012	363,904	5,173	32,101	322,272		(375)	4,733
Shares Issued, Ending Balance at Jun. 30, 2012		5,173,000
Balance, at Dec. 31, 2012	332,153	5,173	29,352	296,797	1,206	(375)	0
Shares Issued, Beginning Balance at Dec. 31, 2012	5,173,450	5,173,450
Net income	27,301			27,301			0
Dividends paid	(28,094)			(28,094)
Change in unrealized net gain on available-for-sale securities	1,429				1,429
Deferred stock unit grant	394		394
Other	0		(1)			1
Balance, at Jun. 30, 2013	$ 333,183	$ 5,173	$ 29,745	$ 296,004	$ 2,635	$ (374)	$ 0
Shares Issued, Ending Balance at Jun. 30, 2013	5,173,450	5,173,450