8.	DETAIL OF CERTAIN BALANCE SHEET ACCOUNTS:

Activity in Quanta’s current and long-term allowance for doubtful accounts consisted of the following (in thousands):


	December 31,
	2015			2014
Balance at beginning of year	$	6,174		$	5,215
Charged to bad debt expense and provision for long-term contract receivable		224			103,871
Deductions for uncollectible receivables written off, net of recoveries		(1,172	)		(102,912	)

Balance at end of year	$	5,226		$	6,174

Included in the 2014 amounts charged and written off was the $102.5 million charge to provision for long-term contract receivable and subsequent write-off related to the Sunrise Powerlink project. See Legal Proceedings — Sunrise Powerlink Arbitration in Note 15 for more information.

Contracts in progress were as follows (in thousands):


	December 31,
	2015			2014
Costs incurred on contracts in progress	$	5,725,078		$	6,603,351
Estimated earnings, net of estimated losses		756,974			1,111,657

		6,482,052			7,715,008
Less — Billings to date		(6,563,537	)		(7,675,674	)

	$	(81,485	)	$	39,334

Costs and estimated earnings in excess of billings on uncompleted contracts	$	317,745		$	290,447
Less — Billings in excess of costs and estimated earnings on uncompleted contracts		(399,230	)		(251,113	)

	$	(81,485	)	$	39,334

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


	Estimated Useful Lives in Years	December 31,
	Estimated Useful Lives in Years	2015			2014
Land	N/A	$	41,428		$	40,657
Buildings and leasehold improvements	5-30		116,697			93,042
Operating equipment and vehicles	5-25		1,517,630			1,459,409
Office equipment, furniture and fixtures and information technology systems	3-15		137,670			119,529
Construction work in progress	N/A		43,806			38,496

			1,857,231			1,751,133
Less — Accumulated depreciation and amortization			(755,272	)		(651,559	)

Property and equipment, net		$	1,101,959		$	1,099,574

Accounts payable and accrued expenses consisted of the following (in thousands):


	December 31,
	2015		2014
Accounts payable, trade	$	452,295	$	477,370
Accrued compensation and related expenses		159,045		164,777
Accrued insurance, current portion		61,327		49,309
Deferred revenues, current portion		8,010		13,082
Income and franchise taxes payable		3,923		20,946
Other accrued expenses		97,534		99,747

	$	782,134	$	825,231