XML 120 R107.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock-Based Compensation (Details 2) - Stock Options [Member]
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-Based Compensation Arrangement By Share-Based Payment Award [Line Items]      
Dividend yield
Expected life 7 years 7 years 7 years
Expected volatility 34.63% 43.22% 51.24%
Risk-free interest rate 2.04% 1.65% 1.63%