Quarterly report pursuant to Section 13 or 15(d)

Earnings Per Share (Narrative) (Details)

v3.8.0.1
Earnings Per Share (Narrative) (Details) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Stock repurchase plan, authorized amount $ 700,000,000   $ 700,000,000  
Aggregate shares repurchased under stock repurchase plan (in shares)     21,658,035  
Stock purchase value     $ 562,064,000  
Stock Repurchased During Period, Shares     665,095  
Stock Repurchased During Period, Value     $ 35,542,000 $ 11,000
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 931,524 575,541 887,508 506,437
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 36,589 71,243 43,292 68,897