Stock-Based Compensation (Schedule of Restricted Stock Awards) (Details) (Restricted Stock [Member], USD $)	6 Months Ended
	Jun. 30, 2012
Grant Date - 3/15/2011 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date	March 15, 2011
Shares	24,836
Grant Date Fair Value	$ 38.46
Aggregate Fair Value	$ 955,193
Vesting Date	March 15, 2015
Grant Date - 2/1/2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date	February 1, 2012
Shares	66,000
Grant Date Fair Value	$ 30.15
Aggregate Fair Value	1,989,900
Vesting Date	February 1, 2016
Grant Date - 3/6/2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date	March 6, 2012
Shares	18,347
Grant Date Fair Value	$ 27.49
Aggregate Fair Value	504,359
Vesting Date	March 6, 2016
Grant Date - 5/23/2012 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date	May 23, 2012
Shares	8,000
Grant Date Fair Value	$ 28.05
Aggregate Fair Value	$ 224,400
Vesting Date	May 23, 2016