Subsequent Events (Details Textual) (USD $)	1 Months Ended		3 Months Ended
	Apr. 30, 2013	Jan. 31, 2013	Mar. 31, 2013	Mar. 31, 2012
Subsequent Event (Textual) [Abstract]
Dividends per common share	$ 0.225	$ 0.225	$ 0.23	$ 0.15
Date of dividend payable	Jun. 21, 2013
Record date of dividend payable	May 17, 2013