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	41,125			41,125
Dividends paid	(42,145)			(42,145)
Change in unrealized net gain on available-for-sale securities	(996)				(996)
Change in value of interest rate cap	0
Deferred stock unit grant	394		394
Other	0		(1)			1
Balance, at Sep. 30, 2013	330,531	5,173	29,745	295,777	210	(374)
Shares Issued, Ending Balance (in shares) at Sep. 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	49,764			49,764
Dividends paid	(49,825)			(49,825)
Change in unrealized net gain on available-for-sale securities	2,644				2,644
Change in value of interest rate cap	(183)				(183)
Deferred stock unit grant	394		394
Balance, at Sep. 30, 2014	$ 336,375	$ 5,173	$ 30,139	$ 297,454	$ 3,983	$ (374)
Shares Issued, Ending Balance (in shares) at Sep. 30, 2014	5,173,450	5,173,450