Earnings per Share (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Restricted Shares [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Incremental common shares attributable to share-based payment arrangements	286,279	152,546	273,563	205,876
Stock Options [Member]
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Incremental common shares attributable to share-based payment arrangements	174,843	196,649	186,661	246,865