Consolidated Statements of Operations (USD $) In Thousands, except Share data, 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
Net interest income:
Interest income from securities	$ 3,120	$ 3,674	$ 3,230	$ 5,323	$ 5,904	$ 6,316	$ 6,448	$ 6,656	$ 15,347	$ 25,323	$ 18,112
Interest income from commercial mortgage loans	2,930	2,825	2,791	2,234	2,267	2,276	2,297	2,313	10,780	9,153	7,035
Interest income from subordinate loans	7,350	6,144	5,859	5,313	4,817	3,784	3,167	1,909	24,666	13,678	7,338
Interest income from repurchase agreements	366	2,361	2,000	1,559	1,576	1,576	1,552	60	6,286	4,764
Interest expense	(1,463)	(1,768)	(1,929)	(3,242)	(3,618)	(3,716)	(3,781)	(3,339)	(8,402)	(14,454)	(10,714)
Net interest income	12,303	13,236	11,951	11,187	10,946	10,236	9,683	7,599	48,677	38,464	21,771
Operating expenses:
General and administrative expenses (includes equity-based compensation of $3,624 in 2012, $1,788 in 2011 and $1,452 in 2010)	(1,315)	(2,430)	(2,762)	(2,036)	(1,563)	(1,297)	(1,412)	(1,380)	(8,543)	(5,652)	(5,556)
Management fees to related party	(2,040)	(1,518)	(1,292)	(1,289)	(1,297)	(1,241)	(1,101)	(1,088)	(6,139)	(4,728)	(3,339)
Total operating expenses	(3,355)	(3,948)	(4,054)	(3,325)	(2,860)	(2,538)	(2,513)	(2,468)	(14,682)	(10,380)	(8,895)
Interest income from cash balances	6			1	1	2	3	5	7	13	16
Realized gain (loss) on sale of securities				262					262		(33)
Unrealized gain (loss) on securities	16	3,010	2,078	1,385	600	(1,511)	1,366	26	6,489	481	(1,766)
Loss on derivative instruments (includes unrealized gains (losses) of $323 in 2012, $(865) in 2011 and $387 in 2010)	(2)	(87)	(65)	(417)	(18)	(677)	(2,019)	18	(572)	(2,696)	(94)
Net income	8,968	12,211	9,910	9,093	8,669	5,512	6,520	5,180	40,181	25,882	10,999
Preferred dividends									(3,079)
Net income available to common stockholders	$ 7,108	$ 10,992	$ 9,910	$ 9,093	$ 8,669	$ 5,512	$ 6,520	$ 5,180	$ 37,102	$ 25,882	$ 10,999
Basic and diluted net income per share of common stock	$ 0.26	$ 0.52	$ 0.47	$ 0.43	$ 0.41	$ 0.28	$ 0.37	$ 0.29	$ 1.64	$ 1.35	$ 0.87
Basic and diluted weighted average common shares outstanding	27,297,600	20,992,312	20,991,450	20,966,426	20,989,828	19,966,594	17,684,991	17,670,787	22,648,819	18,840,954	12,679,277