Certain Balance Sheet Components Accounts Receivable, Net, Additional Information (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Current retainage contract receivables [Member]
Accounts Receivable, Net (Line Items]
Contract Receivable Retainage, Next Rolling Twelve Months	$ 2,800,000	$ 4,700,000
Unbilled Contracts Receivable	3,300,000	4,000,000
Long Term Retainage Contract Receivables [Member]
Accounts Receivable, Net (Line Items]
Long-term unbilled retainage receivables	4,000,000	4,300,000
Contract Receivable Retainage, Due after Next Rolling Twelve Months	$ 0	$ 0