XML 100 R84.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock-Based Compensation Plans (Narrative) (Details) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Mar. 26, 2012
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Shares available for issuance   125,731    
Fair value of shares vested   $ 5.6 $ 4.4 $ 2.6
Intrinsic value of restricted stock units exercised   $ 6.9 $ 78.7 $ 0.2
Weighted average recognition period   21 months    
Restricted Stock [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Weighted average fair value of shares granted   $ 200.79 $ 196.96 $ 183.30
Restricted Stock Units (RSUs) [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Weighted average fair value of shares granted   $ 206.45 $ 181.04 $ 139.00
Restricted stock units converted to common stock, shares   34,836    
Ten Year Vesting [Member] | Restricted Stock Units (RSUs) [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period   10 years    
Five Year Vesting [Member] | Restricted Stock Units (RSUs) [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period   5 years    
Three Year Vesting [Member] | Restricted Stock Units (RSUs) [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period   4 years    
Minimum [Member] | Fifteen Year Vesting [Member] | Restricted Stock [Member] | Chief Executive Officer [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period   15 years    
Minimum [Member] | Three Year Vesting [Member] | Restricted Stock [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Vesting period   3 years    
Incentive Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of additional shares authorized for issuance 500,000      
Total authorized shares for plan issuance   2,000,000