Accounts Receivable (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Disclosure of Accounts Receivables
Allowance for doubtful accounts	$ (565)	$ (554)
Accounts receivable, Total	29,499	23,109
Trade receivables [Member]
Disclosure of Accounts Receivables
Receivables	3,893	3,389
Contract Receivables [Member]
Disclosure of Accounts Receivables
Receivables	$ 26,171	$ 20,274