Dividends Paid and Declared (Details) (USD $)	3 Months Ended				12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2012
Summary of dividends paid and declared
Record Date	Dec. 31, 2012	Sep. 28, 2012	Jun. 29, 2012	Mar. 30, 2012
Date Paid	Jan. 07, 2013	Oct. 09, 2012	Jul. 09, 2012	Apr. 09, 2012
Amount per share	$ 0.12	$ 0.16	$ 0.16	$ 0.16	$ 0.60