XML 66 R52.htm IDEA: XBRL DOCUMENT v3.8.0.1
Nature of Business and Significant Accounting Policies (Details 5)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Stock Option Awards      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Risk-free interest rate 1.80% 0.90% 0.20%
Expected dividend yield 1.60% 1.60% 1.40%
Expected term 6 years 4 years 3 months 4 years 1 month
Expected volatility 26.60% 25.60% 26.60%
Performance-based restricted stock unit [Member]      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Expected dividend yield 1.60% 1.60% 0.00%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions 0.00% 9.90% 0.00%
Market-based restricted stock unit      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Risk-free interest rate 0.00% 0.90% 0.90%
Expected dividend yield 0.00% 1.60% 1.40%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions 0.00% 9.90% 10.90%
Expected term   4 years 4 years
Expected volatility 0.00% 25.80% 27.50%
Expected volatility of S&P 500 0.00% 25.00% 23.40%
Employee Stock Purchase Plan (ESPP)      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Method Used [Line Items]      
Risk-free interest rate 1.00% 0.50% 0.40%
Expected dividend yield 1.60% 1.50% 1.50%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions 10.50% 10.50% 0.00%
Expected term 6 months 6 months 6 months
Expected volatility 20.90% 27.00% 21.50%