Incentive Plan (Summary of Stock Options Outstanding and Exercisable) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of options outstanding	51,622	80,933
Weighted average remaining contractual life (years), Outstanding	473 days
Weighted average exercise price per option, Outstanding	$ 41.04
Aggregate intrinsic value, Outstanding	$ 1,785,166
$33.18
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, lower limit (in shares)	$ 33.18
Number of options outstanding	4,175
Weighted average remaining contractual life (years), Outstanding	305 days
Weighted average exercise price per option, Outstanding	$ 33.18
Aggregate intrinsic value, Outstanding	$ 177,187
$41.73
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise price, upper limit (in shares)	$ 41.73
Number of options outstanding	47,447
Weighted average remaining contractual life (years), Outstanding	488 days
Weighted average exercise price per option, Outstanding	$ 41.73
Aggregate intrinsic value, Outstanding	$ 1,607,979