Earnings per Share (Changes in Stock Price on Impact Number of Diluted Earnings Per Share and Issuable Upon Conversion of Notes) (Details) (USD $)	6 Months Ended
	Jun. 30, 2011
80.73 [Member]
Share price	$ 80.73
Conversion of stock, shares converted	(1,665)	[1]
Total treasury method incremental shares	23,877	[2]
80.73 [Member] | Shares Underlying 1.875% Convertible Notes [Member]
Conversion of stock, shares converted	23,877
80.73 [Member] | Shares Due to Company Under Notes Hedges [Member]
Total treasury method incremental shares	(25,542)
90.73 [Member]
Share price	$ 90.73
Conversion of stock, shares converted	(19,475)	[1]
Total treasury method incremental shares	279,119	[2]
90.73 [Member] | Shares Underlying 1.875% Convertible Notes [Member]
Conversion of stock, shares converted	279,119
90.73 [Member] | Shares Due to Company Under Notes Hedges [Member]
Total treasury method incremental shares	(298,594)
100.73 [Member]
Share price	$ 100.73
Conversion of stock, shares converted	(33,746)	[1]
Total treasury method incremental shares	483,684	[2]
100.73 [Member] | Shares Underlying 1.875% Convertible Notes [Member]
Conversion of stock, shares converted	483,684
100.73 [Member] | Shares Due to Company Under Notes Hedges [Member]
Total treasury method incremental shares	(517,430)
110.73 [Member]
Share price	$ 110.73
Conversion of stock, shares converted	74,133	[1]
Warrant shares	119,575
Total treasury method incremental shares	770,874	[2]
110.73 [Member] | Shares Underlying 1.875% Convertible Notes [Member]
Conversion of stock, shares converted	651,299
110.73 [Member] | Shares Due to Company Under Notes Hedges [Member]
Total treasury method incremental shares	(696,741)
120.73 [Member]
Share price	$ 120.73
Conversion of stock, shares converted	261,788
Warrant shares	316,987
Total treasury method incremental shares	1,108,135	[2]
120.73 [Member] | Shares Underlying 1.875% Convertible Notes [Member]
Conversion of stock, shares converted	791,148
120.73 [Member] | Shares Due to Company Under Notes Hedges [Member]
Total treasury method incremental shares	(846,347)
130.73 [Member]
Share price	$ 130.73
Conversion of stock, shares converted	420,735	[1]
Warrant shares	484,198
Total treasury method incremental shares	1,393,800	[2]
130.73 [Member] | Shares Underlying 1.875% Convertible Notes [Member]
Conversion of stock, shares converted	909,602
130.73 [Member] | Shares Due to Company Under Notes Hedges [Member]
Total treasury method incremental shares	(973,065)

[1] Represents the number of incremental shares to be issued by the Company upon conversion of the 1.875% Convertible Notes, assuming concurrent settlement of the note hedges and warrants.

[2] Represents the number of incremental shares that must be included in the calculation of fully diluted shares under U.S. GAAP.