XML 72 R48.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock Based Compensation Status of Nonvested Restricted Shares (Details) - Restricted Stock [Member] - $ / shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number 180,692 225,624
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value $ 81.13 $ 71.61
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Issues in Period 106,113  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Issues in Period, Weighted Average Grant Date Fair Value $ 87.09  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period 147,687  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value $ 70.90  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period 3,358  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value $ 84.97