Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Schedule Of Weighted Average Assumptions For Restricted Stock Units) (Details)

v3.10.0.1
Stock-Based Compensation (Schedule Of Weighted Average Assumptions For Restricted Stock Units) (Details) - Restricted Stock Units [Member] - $ / shares
3 Months Ended 9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period, years 3 years 6 months 3 days 4 years 10 days 3 years 10 months 17 days 3 years 10 months 12 days
Expected annual dividend yield 1.01% 1.23% 1.15% 1.30%
Estimated average grant date fair value per restricted stock unit (in dollars per share) $ 84.32 $ 55.61 $ 73.10 $ 52.65