SUPPLEMENTAL BALANCE SHEET INFORMATION

Allowance for Doubtful Accounts

Activity in the allowance for doubtful accounts is summarized as follows (in thousands):



	Years Ended December 31,
	2015			2014			2013
Balance, at beginning of year	$	19,307		$	3,441		$	2,953
Bad debt expense ⁽¹⁾⁽²⁾	6,369			21,911			1,043
Write-offs and adjustments ⁽¹⁾⁽²⁾	(11,152		)	(6,045		)	(555		)
Balance, at end of year ⁽³⁾	$	14,524		$	19,307		$	3,441

__________________________


⁽¹⁾	The Company recorded bad debt expense of $1.2 million and $11.9 million in 2015 and 2014, respectively, as part of the 2014 Restructuring (see Note 3) and was primarily due to the exiting of certain low-return businesses mainly in foreign locations.


⁽²⁾	The Company recorded bad debt expense of $2.9 million in 2015 related to long-dated receivables within the Corrosion Protection segment.


⁽³⁾	December 31, 2015 and 2014 balances include $7.5 million related to long-dated receivables, some of which were in litigation or dispute, within the Infrastructure Solutions segment.

Costs and Estimated Earnings on Uncompleted Contracts

Costs and estimated earnings on uncompleted contracts consisted of the following (in thousands):



	December 31,
	2015			2014
Costs incurred on uncompleted contracts	$	818,008		$	795,139
Estimated earnings to date	159,321			158,982
Subtotal	977,329			954,121
Less – billings to date	(975,663		)	(903,098		)
Total	$	1,666		$	51,023
Included in the accompanying balance sheets:
Costs and estimated earnings in excess of billings	89,141			94,045
Billings in excess of costs and estimated earnings	(87,475		)	(43,022		)
Total	$	1,666		$	51,023

Costs and estimated earnings in excess of billings represent work performed that could not be billed either due to contract stipulations or the required contractual documentation has not been finalized. Substantially all unbilled amounts are expected to be billed and collected within one year.

Inventories

Inventories are summarized as follows (in thousands):



	December 31,
	2015		2014
Raw materials and supplies	$	23,467	$	22,807
Work-in-process	3,612		13,179
Finished products	6,789		9,692
Construction materials	13,911		13,514
Total	$	47,779	$	59,192

Property, Plant and Equipment

Property, plant and equipment consisted of the following (in thousands):



	Estimated Useful Lives (Years)			December 31,
	Estimated Useful Lives (Years)			2015			2014
Land and land improvements				$	10,348		$	12,021
Buildings and improvements	5	—	40	55,981			62,548
Machinery and equipment	4	—	10	173,898			185,003
Furniture and fixtures	3	—	10	30,048			27,115
Autos and trucks	3	—	10	50,200			51,635
Construction in progress				11,661			15,400
Subtotal				332,136			353,722
Less – Accumulated depreciation				(187,303		)	(185,509		)
Total				$	144,833		$	168,213

Depreciation expense was $30.6 million, $30.2 million and $28.0 million for the years ended December 31, 2015, 2014 and 2013, respectively.

Accrued Expenses

Accrued expenses consisted of the following (in thousands):



	December 31,
	2015		2014
Vendor and other accrued expenses	$	56,570	$	49,499
Estimated casualty and healthcare liabilities	15,255		17,780
Job costs	12,403		13,718
Accrued compensation	22,184		21,033
Income tax payable and deferred income taxes	6,539		9,587
Total	$	112,951	$	111,617