Incentive Plans (Schedule Of Stock Options Awards Activity) (Details) (Stock Options [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 years
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Outstanding at beginning of year	507,539
Number of Options awarded	86,903
Number of Options expired and forfeited
Options exercised	(30,398)
Number of Shares, Outstanding and expected to vest at end of year	564,044
Number of Shares, Exercisable at end of year	26,905
Weighted Average Exercise Price, Outstanding at beginning of year	$ 23.11
Weighted Average Exercise Price, Options awarded	$ 98.69
Weighted Average Exercise Price, Options expired and forfeited
Weighted Average Exercise Price, Options exercised	$ 20.36
Weighted Average Exercise Price, Outstanding and expected to vest at end of year	$ 34.90
Weighted Average Exercise Price, Exercisable at end of year	$ 22.64
Weighted Average Remaining Contractual Life, Outstanding and expected to vest at end of year	8.10
Weighted Average Remaining Contractual Life, Exercisable at end of year	7.63
Aggregate Intrinsic Value, Outstanding and expected to vest at end of year	$ 30,786
Aggregate Intrinsic Value, Exercisable at end of year	$ 1,798