Subsequent Events (Details) (USD $)	0 Months Ended
	Aug. 07, 2013	May 07, 2013	Feb. 13, 2013
Subsequent Events [Abstract]
Dividends declared date	Aug. 07, 2013	May 07, 2013	Feb. 12, 2013
Dividend amount to be paid, per common share	$ 0.2475	$ 0.2400	$ 0.2325
Date dividend is payable	Sep. 03, 2013	Jun. 04, 2013	Mar. 04, 2013
Date shareholders must be on record for dividend	Aug. 19, 2013	May 20, 2013	Feb. 25, 2013