v3.8.0.1
Share-Based Payments (Summary of the Status of the Company's Employee Stock Option Grants) (Details) - Employee stock options
12 Months Ended
Dec. 31, 2017
$ / shares
shares
Shares  
Outstanding (in shares) | shares 6,738,802
Granted (in shares) | shares 410,501
Exercised (in shares) | shares (2,385,170)
Forfeited (in shares) | shares (28,910)
Expired (in shares) | shares (5,821)
Outstanding (in shares) | shares 4,729,402
Exercisable (in shares) | shares 3,248,670
Weighted Average Exercise Price  
Outstanding (in dollars per share) | $ / shares $ 63.53
Granted (in dollars per share) | $ / shares 110.15
Exercised (in dollars per share) | $ / shares 63.80
Forfeited (in dollars per share) | $ / shares 69.23
Expired (in dollars per share) | $ / shares 83.29
Outstanding (in dollars per share) | $ / shares 67.38
Exercisable (in dollars per share) | $ / shares $ 61.91