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
Balance, at Dec. 31, 2012	$ 332,153	$ 5,173	$ 29,352	$ 296,797	$ 1,206	$ (375)
Shares Issued, Beginning Balance (in shares) at Dec. 31, 2012		5,173,000
Net income	27,301			27,301
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			(1)			1
Change in value of interest rate cap	0
Balance, at Jun. 30, 2013	333,183	5,173	29,745	296,004	2,635	(374)
Shares Issued, Ending Balance (in shares) at Jun. 30, 2013		5,173,000
Balance, at Dec. 31, 2013	333,581	5,173	29,745	297,515	1,522	(374)
Shares Issued, Beginning Balance (in shares) at Dec. 31, 2013	5,173,450	5,173,450
Net income	32,072			32,072
Dividends paid	(33,213)			(33,213)
Change in unrealized net gain on available-for-sale securities	4,207				4,207
Deferred stock unit grant	394		394
Change in value of interest rate cap	(153)				(153)
Balance, at Jun. 30, 2014	$ 336,888	$ 5,173	$ 30,139	$ 296,374	$ 5,576	$ (374)
Shares Issued, Ending Balance (in shares) at Jun. 30, 2014	5,173,450	5,173,450