Business Description and Summary of Significant Accounting Policies Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	$ 23,969	$ 24,811
Allowance for Doubtful Accounts Receivable, Current	(102)	(143)
Accounts Receivable, Net, Current	23,867	24,668
Billed Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	14,965	16,447
Unbilled Revenues [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts Receivable, Gross, Current	$ 9,004	$ 8,364