Description of Business and Summary of Significant Accounting Policies (Accounts Receivables and Allowances) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Net, Current	$ 37,298,000	$ 31,133,000
Deferred revenue included in accounts receivables	7,000,000	8,300,000
Bad debt expense	442,000	976,000	1,143,000
Billed Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Net, Current	28,500,000	25,900,000
Unbilled Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Net, Current	$ 8,800,000	$ 5,200,000