Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation (Schedule of Stock-Based Compensation Expense) (Details)

v3.8.0.1
Stock-Based Compensation (Schedule of Stock-Based Compensation Expense) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Pre-tax stock-based compensation expense $ 11,286 $ 10,986 $ 11,672
Income tax benefits (1,778) (3,969) (4,044)
Total stock-based compensation expense, net of tax 9,508 7,017 7,628
Cost of Sales [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Pre-tax stock-based compensation expense 243 233 326
Selling, General and Administrative Expense [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Pre-tax stock-based compensation expense $ 11,043 $ 10,753 $ 11,346