Stock-Based Compensation (Option Activity) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Stock-Based Compensation [Abstract]
Number of Stock Options, Outstanding at December 31, 2010, in shares	24,497
Number of Stock Options, Granted, in shares	2,540
Number of Stock Options, Exercised, in shares	(2,257)
Number of Stock Options, Terminated, in shares	(221)
Number of Stock Options Outstanding at December 31, 2011, in shares	24,559
Number of Stock Options, Vested and expected-to-vest at December 31, 2011, in shares	24,476
Number of Stock Options, Vested at December 31, 2011, in shares	18,356
Weighted Average Exercise Price, Outstanding at December 31, 2010, in dollars per share	$ 75.90
Weighted Average Exercise Price, Granted, in dollars per share	$ 79.60
Weighted Average Exercise Price, Exercised, in dollars per share	$ 51.56
Weighted Average Exercise Price, Terminated, in dollars per share	$ 83.77
Weighted Average Exercise Price, Outstanding at December 31, 2011, in dollars per share	$ 78.45
Weighted Average Exercise Price, Vested and expected-to-vest at December 31, 2011, in dollars per share	$ 78.45
Weighted Average Exercise Price, Vested at December 31, 2011, in dollars per share	$ 78.41
Weighted Average Remaining Contractual Life, Outstanding at December 31, 2011, in years	5.7
Weighted Average Remaining Contractual Life, Vested and expected-to-vest at December 31, 2011, in years	5.6
Weighted Average Remaining Contractual Life, Vested at December 31, 2011, in years	4.8
Aggregate Intrinsic Value, Outstanding at December 31, 2011	$ 204.1
Aggregate Intrinsic Value, Vested and expected-to-vest at December 31, 2011	204.0
Aggregate Intrinsic Value, Vested at December 31, 2011	$ 187.1