Incentive Plan (Summary Of Stock Options Outstanding And Exercisable) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number outstanding (shares)	53,972	80,933
Weighted-average remaining contractual life (years)	566 days
Weighted average exercise price, Outstanding ($ per share)	$ 41.07
Aggregate intrinsic value	$ 1,308,896
$33.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit	$ 33.18
Exercise price, upper limit	$ 33.18
Number outstanding (shares)	4,175
Weighted-average remaining contractual life (years)	397 days
Weighted average exercise price, Outstanding ($ per share)	$ 33.18
Aggregate intrinsic value	$ 134,185
$41.73
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit	$ 41.73
Exercise price, upper limit	$ 41.73
Number outstanding (shares)	49,797
Weighted-average remaining contractual life (years)	580 days
Weighted average exercise price, Outstanding ($ per share)	$ 41.73
Aggregate intrinsic value	$ 1,174,711