Quarterly report pursuant to Section 13 or 15(d)

Earnings Per Share (Narrative) (Details)

v3.10.0.1
Earnings Per Share (Narrative) (Details) - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Stock repurchase plan, authorized amount $ 900,000,000   $ 900,000,000  
Aggregate shares repurchased under stock repurchase plan (in shares)     22,918,221  
Stock purchase value     $ 669,285,000  
Stock Repurchased During Period, Shares 759,896   1,260,186 665,095
Stock Repurchased During Period, Value $ 67,116,000   $ 107,222,000 $ 35,542,000
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 216,386 931,524 325,410 887,508
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 23,971 36,589 23,971 43,292