Description of Business and Summary of Significant Accounting Policies (Accounts Receivables and Allowances) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deferred revenue included in accounts receivables	$ 6,000	$ 6,900
Trade account receivable	62,713	47,171
Allowance for doubtful accounts	2,833	3,388
Bad debt expense	1,515	3,111	$ 1,600
Billed Revenues
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade account receivable	51,800	36,700
Unbilled Revenues
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade account receivable	$ 10,900	$ 10,500