Stock-Based Compensation (Schedule of Performance Unit Awards) (Details) (Performance Shares [Member], USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Incentive Plan, 2011-2013 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date	March 15, 2011
Units	34,002
Grant Date Fair Value	$ 38.46
Aggregate Fair Value	$ 1,308
Incentive Plan, 2012-2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date	March 6, 2012
Units	43,042
Grant Date Fair Value	$ 27.49
Aggregate Fair Value	1,183
Incentive Plan, 2013-2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date	February 27, 2013
Units	31,418
Grant Date Fair Value	$ 42.49
Aggregate Fair Value	$ 1,335