Detail of Certain Balance Sheet Accounts

12 Months Ended

Dec. 31, 2011

Detail of Certain Balance Sheet Accounts

Detail of Certain Balance Sheet Accounts

8. Detail of Certain Balance Sheet Accounts

        Activity in our allowance for doubtful accounts consists of the following (in thousands):

	December 31,
	2011			2010			2009
Balance at beginning of year	$	5,096		$	7,253		$	5,250
Additions for bad debt expense		936			364			3,283
Deductions for uncollectible receivables written off, net of recoveries		(833	)		(2,699	)		(1,313	)
Allowance for doubtful accounts of acquired companies at date of acquisition		142			178			33
Balance at end of year	$	5,341		$	5,096		$	7,253

        Other current liabilities consist of the following (in thousands):

	December 31,
	2011		2010
Accrued warranty costs	$	8,363	$	9,925
Accrued backcharges		—		6,489
Accrued job losses		2,060		1,670
Accrued rent and lease obligations		2,793		1,158
Accrued sales and use tax		1,498		1,500
Deferred revenue		1,607		1,692
Other current liabilities		11,151		8,382
	$	27,472	$	30,816

        Contracts in progress are as follows (in thousands):

	December 31,
	2011			2010
Costs incurred on contracts in progress	$	837,288		$	1,127,688
Estimated earnings, net of losses		54,911			202,295
Less—Billings to date		(936,766	)		(1,366,757	)
	$	(44,567	)	$	(36,774	)
Costs and estimated earnings in excess of billings	$	27,163		$	26,648
Billings in excess of costs and estimated earnings		(71,730	)		(63,422	)
	$	(44,567	)	$	(36,774	)