Distributions (Details 1) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Summary of payment of dividends to preferred shareholders
Amount of distributions paid for preferred stock	$ 7,556,588	$ 7,556,588	$ 4,325,109
Preferred stock, dividend declared per share, paid	$ 2.0625	$ 2.0625	$ 2.0625
1/18/2012 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date			Jan. 18, 2012
Record Date			Feb. 15, 2012
Payment Date			Mar. 15, 2012
Amount of distributions paid for preferred stock			690,319
Preferred stock, dividend declared per share, paid			$ 0.515625
4/17/2012 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date			Apr. 17, 2012
Record Date			May 15, 2012
Payment Date			Jun. 15, 2012
Amount of distributions paid for preferred stock			930,716
Preferred stock, dividend declared per share, paid			$ 0.515625
7/9/2012 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date			Jul. 09, 2012
Record Date			Aug. 15, 2012
Payment Date			Sep. 17, 2012
Amount of distributions paid for preferred stock			1,244,616
Preferred stock, dividend declared per share, paid			$ 0.515625
10/1/2012 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date			Oct. 01, 2012
Record Date			Nov. 15, 2012
Payment Date			Dec. 17, 2012
Amount of distributions paid for preferred stock			1,459,458
Preferred stock, dividend declared per share, paid			$ 0.515625
1/16/2013 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date		Jan. 16, 2013
Record Date		Feb. 15, 2013
Payment Date		Mar. 15, 2013
Amount of distributions paid for preferred stock		1,889,147
Preferred stock, dividend declared per share, paid		$ 0.515625
4/8/2013 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date		Apr. 08, 2013
Record Date		May 15, 2013
Payment Date		Jun. 17, 2013
Amount of distributions paid for preferred stock		1,889,147
Preferred stock, dividend declared per share, paid		$ 0.515625
7/1/2013 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date		Jul. 01, 2013
Record Date		Aug. 15, 2013
Payment Date		Sep. 16, 2013
Amount of distributions paid for preferred stock		1,889,147
Preferred stock, dividend declared per share, paid		$ 0.515625
10/1/2013 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date		Oct. 01, 2013
Record Date		Nov. 15, 2013
Payment Date		Dec. 16, 2013
Amount of distributions paid for preferred stock		1,889,147
Preferred stock, dividend declared per share, paid		$ 0.515625
1/15/2014 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date	Jan. 15, 2014
Record Date	Feb. 18, 2015
Payment Date	Mar. 17, 2014
Amount of distributions paid for preferred stock	1,889,147
Preferred stock, dividend declared per share, paid	$ 0.515625
4/1/2014 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date	Apr. 01, 2014
Record Date	May 15, 2014
Payment Date	Jun. 16, 2014
Amount of distributions paid for preferred stock	1,889,147
Preferred stock, dividend declared per share, paid	$ 0.515625
7/1/2014 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date	Jul. 01, 2014
Record Date	Aug. 15, 2014
Payment Date	Sep. 15, 2014
Amount of distributions paid for preferred stock	1,889,147
Preferred stock, dividend declared per share, paid	$ 0.515625
10/1/2014 [Member]
Summary of payment of dividends to preferred shareholders
Declaration Date	Oct. 01, 2014
Record Date	Nov. 17, 2014
Payment Date	Dec. 15, 2014
Amount of distributions paid for preferred stock	$ 1,889,147
Preferred stock, dividend declared per share, paid	$ 0.515625