Incentive Plan (Summary Of Incentive Award Plan's Stock Option) (Details) (USD $)	9 Months Ended
	Sep. 30, 2011
Incentive Plan [Abstract]
Options outstanding, beginning of period, Shares	470,264
Exercised, Shares	(90,171)
Cancelled / Forfeited, Shares	(8,727)
Options outstanding, end of period, Shares	371,366
Exercisable, end of period, Shares	326,189
Options outstanding, beginning of period, Weighted average exercise price	$ 28.35
Exercised, Weighted average exercise price	$ 37.89
Cancelled / Forfeited, Weighted average exercise price	$ 41.73
Options outstanding, end of period, Weighted average exercise price	$ 25.73
Exercisable, end of period, Weighted average exercise price	$ 23.52