Shareholders' Equity Textuals (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
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	3,161,397
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	43,078	42,067
Restricted Stock Units, Grants in Period, Weighted Average Grant Date Fair Value	$ 169.37	$ 150.11
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	5 years
Restricted Stock Units, Intrinsic Value	$ 7,300,000	$ 6,300,000
Share-based Compensation Expense for Restricted Stock Units	$ 5,300,000	$ 4,600,000
Share Repurchase Program and Treasury Stock [Abstract]
Stock Repurchase Program, Authorized Amount	2,250,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	437,000,000
Shares Repurchased Under Share Repurchase Program	20,100,000
Repurchases of Common Stock, Value	$ (278,672,000)	$ (204,578,000)	$ (239,998,000)
Repurchases of Common Stock, Shares	(1,637,827)	(1,285,827)
Treasury Stock Acquired, Average Cost Per Share	$ 170.13	$ 159.08
Exercise of stock options and restricted stock units, shares	457,732	450,613
Shareholders Rights Plan [Abstract]
Rights Issued Per Common Share	one