Stock-Based Compensation (Summary Of Stock Option Activity) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Stock-Based Compensation [Abstract]
Outstanding, Number of Options, beginning balance	6,912,014	7,986,876	12,486,397
Exercised, Number of Options	(596,682)	(1,069,537)	(2,903,000)
Cancelled, forfeited or expired, Number of Options	(11,600)	(5,325)	(2,940,521)
Options granted, Number of Options	0	0	1,344,000
Outstanding, Number of Options, ending balance	6,303,732	6,912,014	7,986,876
Exercisable, Number of Options	5,855,732
Vested or expected to vest, Number of Options	6,302,970
Outstanding, Weighted Average Exercise Price, beginning balance	$ 24.51	$ 24.43	$ 23.12
Exercised, Weighted Average Exercise Price	$ 21.84	$ 23.88	$ 18.89
Cancelled, forfeited or expired, Weighted Average Exercise Price	$ 27.69	$ 27.25	$ 22.50
Options Granted, Weighted Average Exercise Price	$ 0.00	$ 0.00	$ 20.38
Outstanding, Weighted Average Exercise Price, ending balance	$ 24.76	$ 24.51	$ 24.43
Exercisable, Weighted Average Exercise Price	$ 25.09
Vested or expected to vest, Weighted Average Exercise Price	$ 24.76
Outstanding, Weighted Average Remaining Contractual Life (years)	2.62	3.41	4.23	2.74
Exercisable, Weighted Average Remaining Contractual Life (years)	2.37
Vested or expected to vest, Weighted Average Remaining Contractual Life (years)	2.62
Outstanding, Aggregate Intrinsic Value	$ 12,469,431	$ 19,658,512	$ 14,398,197	$ 1,526,570
Exercisable, Aggregate Intrinsic Value	10,081,591
Vested or expected to vest, Aggregate Intrinsic Value	$ 12,465,371