Detail of Certain Balance Sheet Accounts

12 Months Ended

Dec. 31, 2019

DETAIL OF CERTAIN BALANCE SHEET ACCOUNTS:

Activity in Quanta’s allowance for doubtful accounts consisted of the following (in thousands):



	December 31,
	2019			2018
Balance at beginning of year	$	5,839		$	4,465
Charges to bad debt expense	11,249			7,169
Direct write-offs charged against the allowance	(7,690		)	(5,795		)
Balance at end of year	$	9,398		$	5,839

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



	Estimated Useful	December 31,
	Lives in Years	2019			2018
Land	N/A	$	67,560		$	61,305
Buildings and leasehold improvements	5-30	231,920			208,974
Operating equipment and vehicles	1-25	2,068,644			1,865,917
Office equipment, furniture and fixtures and information technology systems	3-10	228,329			212,769
Construction work in progress	N/A	26,236			19,507
Finance lease assets and rental purchase options (see Note 9)	5-20	14,162			—
Property and equipment, gross		2,636,851			2,368,472
Less — Accumulated depreciation and amortization		(1,250,197		)	(1,092,440		)
Property and equipment, net of accumulated depreciation		$	1,386,654		$	1,276,032

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



	December 31,
	2019		2018
Accounts payable, trade	$	798,718	$	786,546
Accrued compensation and related expenses	316,237		279,107
Contingent consideration liabilities, current portion	77,618		—
Accrued insurance, current portion	69,307		56,552
Income and franchise taxes payable	58,353		13,094
Unearned revenues, current portion	33,192		40,083
Sales and use taxes payable	28,721		35,736
Other accrued expenses	107,413		103,402
Accounts payable and accrued expenses	$	1,489,559	$	1,314,520