CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $)	Redeemable Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2009	$ 10,315	$ 8,725,127	$ 80,990,686	$ 34,365,640	$ 1,449,030	$ 125,540,798
Balance (in shares) at Dec. 31, 2009	17,192	14,541,878
Issue of share capital	3,539	5,139	117,441	0	0	126,119
Issue of share capital (in shares)	5,899	8,565
Conversion of preferred stock	(2,970)	2,970	0	0	0	0
Conversion of preferred stock (in shares)	(4,950)	4,950
Buyback of preferred stock	(814)	0	(15,982)	0	0	(16,796)
Buyback of preferred stock (in shares)	(1,357)	0
Net income	0	0	0	6,292,025	151,137	6,443,162
Dividends declared	0	0	0	(4,367,959)	0	(4,367,959)
Stock-based compensation	0	0	257,799	0	0	257,799
Balance at Dec. 31, 2010	10,070	8,733,236	81,349,944	36,289,706	1,600,167	127,983,123
Balance (in shares) at Dec. 31, 2010	16,784	14,555,393
Issue of share capital	5,007	6,694	99,284	0	0	110,985
Issue of share capital (in shares)	8,345	11,158
Conversion of preferred stock	(1,287)	1,287	0	0	0	0
Conversion of preferred stock (in shares)	(2,145)	2,145
Buyback of preferred stock	(334)	0	(4,665)	0	0	(4,999)
Buyback of preferred stock (in shares)	(557)	0
Net income	0	0	0	6,113,218	438,762	6,551,980
Dividends declared	0	0	0	(4,371,981)	(482,400)	(4,854,381)
Stock-based compensation	0	0	494,648	0	0	494,648
Balance at Dec. 31, 2011	13,456	8,741,217	81,939,211	38,030,943	1,556,529	130,281,356
Balance (in shares) at Dec. 31, 2011	22,427	14,568,696
Issue of share capital	6,850	13,013	164,391	0	0	184,254
Issue of share capital (in shares)	11,417	21,686
Conversion of preferred stock	(1,577)	1,577	0	0	0	0
Conversion of preferred stock (in shares)	(2,629)	2,629
Buyback of preferred stock	(570)	0	(7,219)	0	0	(7,789)
Buyback of preferred stock (in shares)	(950)	0
Net income	0	0	0	9,315,514	308,495	9,624,009
Dividends declared	0	0	0	(4,381,278)	(72,000)	(4,453,278)
Capital contribution	0	0	0	0	135,000	135,000
Stock-based compensation	0	0	371,038	0	0	371,038
Balance at Dec. 31, 2012	$ 18,159	$ 8,755,807	$ 82,467,421	$ 42,965,179	$ 1,928,024	$ 136,134,590
Balance (in shares) at Dec. 31, 2012	30,265	14,593,011