Shareholders' Equity Textuals (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common Stock, Shares Authorized	125,000,000	125,000,000
Common Stock, Par Value	$ 0.01	$ 0.01
Common Stock, Voting Rights	one
Common Stock Reserved for Issuance to the Stock Option Plans	3,619,129
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred Stock, Shares Authorized	10,000,000	10,000,000
Preferred Stock, Par Value	$ 0.01	$ 0.01
Restricted Stock Units (RSUs) [Abstract]
Restricted Stock Units, Grants in Period	42,067	43,485
Restricted Stock Units, Grants in Period, Weighted Average Grant Date Fair Value	$ 150.11	$ 132.94
Restricted Stock Units, Vesting Period	five
Restricted Stock Units, Intrinsic Value	$ 6,300,000	$ 5,800,000
Share-based Compensation Expense for Restricted Stock Units	$ 4,600,000	$ 4,200,000
Share Repurchase Program and Treasury Stock [Abstract]
Stock Repurchase Program, Authorized Amount	2,250,000,000
Share Repurchase Program Additional Authorized Amount	750,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	716,000,000
Shares Repurchased Under Share Repurchase Program	18,500,000
Repurchases of Common Stock, Value	$ (204,578,000)	$ (239,998,000)	$ (5,988,000)
Repurchases of Common Stock, Shares	(1,285,827)	(1,955,634)
Treasury Stock Acquired, Average Cost Per Share	$ 159.08	$ 122.70
Exercise of stock options and restricted stock units, shares	450,613	527,276
Other Treasury Stock Issuances, Shares	0	2,549
Shareholders Rights Plan [Abstract]
Rights Issued Per Common Share	one
Shareholder Rights Plan Preferred Stock Exercise Price	$ 150,000
Shareholder Rights Plan Ownership Concentration Threshold	15.00%
Stockholder Rights Plan Excemption Ownership Threshold	15.00%
Discount to Current Market Price	50.00%
Additional Subsequent Ownership Interest	2.00%