Annual report pursuant to Section 13 and 15(d)

Stock Plans and Management Compensation (Details 3)

v3.6.0.2
Stock Plans and Management Compensation (Details 3) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-Based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Excess Tax Benefit from Share-Based Compensation, Financing Activities $ 13.4 $ 7.0 $ 8.4
Percentage of Premium Paid Out in Deferred Company Common Stock 20.00%    
Performance Shares [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected Life of Award 2 years 10 months 24 days 2 years 10 months 24 days 2 years 10 months 24 days
Share-Based Compensation Expense $ 6.1 $ 8.0 $ 6.5
Share-Based Compensation Expense, Tax Benefit 2.3 3.0 2.5
Fair Value of Shares Vested During the Period $ 9.1 $ 7.5 $ 7.4
Share-Based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Outstanding at January 1 50,000    
Awarded Grants in Period 217,000    
Forfeited (9,000)    
Vested (167,000)    
Outstanding at December 31 91,000 50,000  
Weighted Average Grant Date Fair Value $ 43.91 $ 49.39  
Awarded - Weighted Average Grant Date Fair Value 37.99    
Forfeited - Weighted Average Grant Date Fair Value 38.49    
Vested - Weighted Average Grant Date Fair Value $ 38.15    
Unrecognized Compensation Cost $ 2.2    
Unrecognized Compensation Cost, Period for Recognition 1 year 7 months 6 days    
Share-based Compensation Award, Tranche Two [Member] | Performance Shares [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted Average Price at Grant Date (in dollars per share) $ 37.76 $ 52.39 $ 40.44
Share-Based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Awarded Grants in Period 37,430 22,990 24,600
Share-based Compensation Award, Tranche One [Member] | Performance Shares [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Weighted Average Price at Grant Date (in dollars per share) $ 38.54 $ 56.17 $ 41.38
Risk-Free Interest Rate 0.80% 1.00% 0.60%
Dividend Yield 1.00% 0.90% 1.00%
Volatility Factor 40.80% 39.20% 43.70%