Detail of Certain Balance Sheet Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Activity in allowance for doubtful accounts
Balance at beginning of year	$ 4,615	$ 5,029	$ 7,200
Additions for bad debt expense	2,753	214	340
Deductions for uncollectible receivables written off, net of recoveries	(1,090)	(770)	(2,689)
Allowance for doubtful accounts of acquired companies at date of acquisition	55	142	178
Balance at end of year	6,333	4,615	5,029
Other current liabilities
Accrued warranty costs	6,781	8,234
Accrued job losses	2,137	1,777
Accrued rent and lease obligations	673	2,793
Accrued sales and use tax	1,710	1,494
Deferred revenue	1,143	1,592
Liabilities due to former owners	2,349
Other current liabilities	12,284	13,959
Total other current liabilities	27,077	29,849
Contracts in progress
Costs incurred on contracts in progress	1,182,085	1,071,406
Estimated earnings, net of losses	134,534	132,096
Less-Billings to date	(1,364,229)	(1,247,535)
Contracts in progress	(47,610)	(44,033)
Costs and estimated earnings in excess of billings	26,204	26,602
Billings in excess of costs and estimated earnings	$ (73,814)	$ (70,635)