Subsequent Events (Details) (USD $)	3 Months Ended			3 Months Ended	1 Months Ended	12 Months Ended
	Mar. 31, 2013	Feb. 15, 2013	Dec. 31, 2012	Mar. 31, 2013 Dividend declared	Feb. 15, 2013 Convertible Notes	Dec. 31, 2012 Convertible Notes	Feb. 15, 2013 Call Options	Dec. 31, 2012 Call Options	Feb. 15, 2013 Warrants	Dec. 31, 2012 Warrants
Subsequent Events (Textuals) [Abstract]
Cash dividend declared per common share	$ 0.30
Subsequent event amount				$ 5,900,000
Conversion rate of common stock shares per $1,000 of principal amount					20.7309	20.7111
Principal amount in conversion feature					$ 1,000	$ 1,000
Conversion price of note		$ 48.24	$ 48.28
Exercise price of call options							$ 48.24	$ 48.28
Exercise price per share of Warrants									61.25	61.31