Incentive Plan (Summary Of Stock Options Outstanding And Exercisable) (Details) - USD ($)	6 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number outstanding (shares)	68,972	80,933
Weighted-average remaining contractual life (years)	543 days
Weighted average exercise price, Outstanding ($ per share)	$ 36.57
Aggregate intrinsic value	$ 2,076,948
$20.37
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit	$ 20.37
Exercise price, upper limit	$ 20.37
Number outstanding (shares)	15,000
Weighted-average remaining contractual life (years)	131 days
Weighted average exercise price, Outstanding ($ per share)	$ 20.37
Aggregate intrinsic value	$ 694,650
$33.18-41.73
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit	$ 33.18
Exercise price, upper limit	$ 41.73
Number outstanding (shares)	53,972
Weighted-average remaining contractual life (years)	657 days
Weighted average exercise price, Outstanding ($ per share)	$ 41.07
Aggregate intrinsic value	$ 1,382,298