Summary of Significant Accounting Policies (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenue Recognition
Warranty period, maximum	1 year
Advertising
Advertising costs	$ 500,000	$ 400,000	$ 400,000
Accounts Receivable and Allowance for Doubtful Accounts
Maximum collection period of majority of customer balances	12 months
Minimum extended period of contracting cycle for long-term contracts	1 year
Minimum extended period for collection of retainage on certain long-term contracts	1 year
Percentage of retainage recorded and expected to be collected within one year	74.00%
Classification of Construction Contract-related Assets and Liabilities
Minimum term of some larger contracts	1 year
Maximum period for settlement of majority of balances under construction contract	1 year
Construction Materials Inventory
Construction materials inventory		$ 4,003,000