Quarterly report pursuant to Section 13 or 15(d)

Earnings Per Share (Narrative) (Details)

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Earnings Per Share (Narrative) (Details) (USD $)
3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Stock repurchase plan, authorized amount 500,000,000  
Aggregate shares repurchased under stock repurchase plan 9,588,798  
Stock purchase value 441,237,000  
Stock Options And Service-Based Restricted Stock Units [Member]
   
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Anti-dilutive securities excluded from computation of earnings per share, number of shares 977,668 282,093
Performance-Based Restricted Stock Units [Member]
   
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]    
Anti-dilutive securities excluded from computation of earnings per share, number of shares 30,865 24,647