Incentive Plan (Summary Of Incentive Award Plan's Stock Option) (Details) (USD $)	9 Months Ended
	Sep. 30, 2012
Incentive Plan [Abstract]
Options outstanding, beginning of period, Shares	337,760
Exercised, Shares	(207,550)
Cancelled / Forfeited, Shares	(301)
Options outstanding, end of period, Shares	129,909
Exercisable, end of period, Shares	129,909
Options outstanding, beginning of period, Weighted average exercise price	$ 24.17
Exercised, Weighted average exercise price	$ 20.11
Cancelled / Forfeited, Weighted average exercise price	$ 41.73
Options outstanding, end of period, Weighted average exercise price	$ 30.62
Exercisable, end of period, Weighted average exercise price	$ 30.62