Stock-Based Compensation Plans (Summary Of Restricted Stock Units Activity) (Details) (USD $)	6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, Nonvested as of December 31	348,000		521,000
Nonvested, Granted	313,000	[1]	5,000	[2]
Vested	143,000	[3]	158,000	[4]
Nonvested, Forfeited	(8,000)		(6,000)
Outstanding, Nonvested as of June 30	510,000		362,000
Weighted Average Grant-Date Fair Value Per Share, Nonvested, Outstanding as of December 31	$ 24.06		$ 19.99
Weighted Average Grant-Date Fair Value Per Share, Nonvested, Granted	$ 106.32	[1]	$ 62.20	[2]
Weighted Average Grant-Date Fair Value Per Share, Nonvested, Vested	$ 21.48	[3]	$ 20.99	[4]
Weighted Average Grant-Date Fair Value Per Share, Nonvested, Forfeited	$ 15.80		$ 13.19
Weighted Average Grant-Date Fair Value Per Share, Nonvested, Outstanding as of September 30	$ 75.43		$ 20.10
Outstanding, Vested as of December 31	428,000		270,000
Outstanding, Vested as of June 30	571,000		428,000
Weighted Average Grant-Date Fair Value Per Share, Vested, Outstanding as of December 31	$ 22.14		$ 22.94
Weighted Average Grant-Date Fair Value Per Share, Vested, Outstanding as of June 30	$ 21.97		$ 22.14
Outstanding, Total as of December 31	776,000		791,000
Total, Granted	313,000	[1]	5,000	[2]
Total, Forfeited	(8,000)		(6,000)
Outstanding, Total as of September 30	1,081,000		790,000
February 18, 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Distribution date of vested restricted stock units	3,000
February 22, 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Distribution date of vested restricted stock units	60,000		60,000
February 22, 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Distribution date of vested restricted stock units	77,000		90,000
February 22, 2017 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Distribution date of vested restricted stock units	6,000		8,000
December 31, 2022, 2023, 2024, 2025, and 2026 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Distribution date of vested restricted stock units	310,000

[1] The distribution date of vested restricted stock units is February 18, 2019 for 3 restricted stock units.  For 310 restricted stock units, the vested restricted stock units will be distributed in equal installments on December 31, 2022, 2023, 2024, 2025 and 2026.

[2] The distribution date of vested restricted stock units is February 22, 2018.

[3] The distribution date of vested restricted stock units is February 22, 2014 for 60 restricted stock units, February 22, 2016 for 77 restricted stock units and February 22, 2017 for 6 restricted stock units.

[4] The distribution date of vested restricted stock units is February 22, 2014 for 60 restricted stock units, February 22, 2016 for 90 restricted stock units and February 22, 2017 for 8 restricted stock units.