Description of Business and Summary of Significant Accounting Policies (Accounts Receivable) (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Changes in the allowance for doubtful accounts      
Allowance for Doubtful Accounts Receivable, Beginning Balance $ 824 $ 705 $ 605
Provision 345 345 229
Deductions (188) (226) (129)
Allowance for Doubtful Accounts Receivable, Ending Balance $ 981 $ 824 $ 705