Parent Company Only Financial Information (Condensed Statements of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Financial Statements [Line Items]
Interest income	$ 8,594	$ 8,927	$ 9,126	$ 9,120	$ 9,770	$ 10,609	$ 10,790	$ 10,488	$ 35,767	$ 41,657	$ 46,049
Interest expense	(1,012)	(1,258)	(1,315)	(1,498)	(1,429)	(1,802)	(1,805)	(1,776)	(5,083)	(6,812)	(10,785)
Net interest income (expense)									30,684	34,845	35,264
Operating expenses	(8,671)	(8,242)	(8,222)	(8,298)	(9,167)	(9,812)	(9,611)	(9,740)	(33,433)	(38,330)	(54,894)
Net income	1,371	824	782	801	1,367	(760)	(605)	1	3,779	3	(31,736)
Dividends declared on preferred shares	462	482	481	466	460	457	448	443	1,891	1,808	1,716
Net income available to common stockholders	909	342	301	335	907	(1,217)	(1,053)	(442)	1,888	(1,805)	(33,452)
Comprehensive Income (loss)									4,937	3,601	(28,125)
Parent Company
Condensed Financial Statements [Line Items]
Interest income									0	0	1
Interest expense									(1,163)	(851)	(1,035)
Net interest income (expense)									(1,163)	(851)	(1,034)
Equity in net earnings (loss) of subsidiary									5,677	1,310	(30,267)
Other income (expense)									(137)	0	0
Operating expenses									(598)	(456)	(435)
Net income									3,779	3	(31,736)
Dividends declared on preferred shares									1,891	1,808	1,716
Net income available to common stockholders									1,888	(1,805)	(33,452)
Comprehensive Income (loss)									$ 4,937	$ 3,601	$ (28,125)