Share-Based Compensation (Schedule Of Summary Of Option Activity Under The SIPs) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Share-Based Compensation [Abstract]
Outstanding at December 31, 2010, Shares	2,020,767
Granted, Shares	154,226
Exercised, Shares	(115,788)
Forfeited or expired, Shares	(15,431)
Outstanding at December 31, 2011, Shares	2,043,774
Vested or expected to vest, Shares	2,009,984
Exercisable, Shares	1,549,376
Outstanding, Weighted-Average Exercise Price	$ 32.17
Granted, Weighted-Average Exercise Price	$ 39.21
Exercised, Weighted-Average Exercise Price	$ 20.18
Forfeited or expired, Weighted-Average Exercise Price	$ 30.95
Outstanding, Weighted-Average Exercise Price	$ 33.39
Vested or expected to vest, Weighted-Average Exercise Price	$ 33.49
Exercisable, Weighted-Average Exercise Price	$ 35.69
Outstanding, Weighted-Average Remaining Contractual Term (Years)	5.62
Vested or expected to vest, Weighted-Average Remaining Contractual Term (Years)	5.57
Exercisable, Weighted-Average Remaining Contractual Term (Years)	4.77
Outstanding, Aggregate Intrinsic Value	$ 10,537
Vested or expected to vest, Aggregate Intrinsic Value	10,240
Exercisable, Aggregate Intrinsic Value	$ 5,681