Summary of Significant Accounting Policies - Accounts Receivable (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Accounts Receivable [Abstract]
Contract receivable retention	$ 8,213,000	$ 5,977,000
Accounts receivable, retention to be collected after 2012	2,500,000
Accounts receivable, long-term	$ 1,410,000	$ 1,410,000