SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2017

SIGNIFICANT ACCOUNTING POLICIES

Schedule of change in allowance for doubtful accounts

The change in allowance for doubtful accounts is as follows:

	For the year ended December 31,
	2017		2016		2015
	(in thousands)
Balance at beginning of year	$	2,144	$	2,351	$	3,169
Provisions for bad debts, included in selling, general and administrative		1,542		2,385		3,179
Uncollectible receivables written off		(707)		(2,592)		(3,997)
Balance at end of year	$	2,979	$	2,144	$	2,351

Schedule of estimated useful life of property and equipment

Asset Classification	Useful Life (years)
Land	Indefinite
Buildings and leasehold improvements	30 or lease term
Vehicles and equipment	4 - 7
Machinery and equipment	2 - 15
Computer equipment and software	3 - 4
Office furniture and equipment	7
Disposal wells	7 - 10
Helicopters	7

Summary of change in asset retirement obligations

	For the year ended December 31,
	2017		2016
	(in thousands)
Balance at beginning of year	$	1,668	$	1,483
Accretion expense, included in depreciation and amortization expense		178		155
Change in estimate		—		30
Balance at end of year	$	1,846	$	1,668

Summary of cash flows from discontinued operations

	Year Ended
	December 31, 2015
	(in thousands)
Net cash provided by operating activities	$	400
Net cash provided by investing activities		679
Net cash used in financing activities		(1,678)
Effect of exchange rate changes on cash		75
Net decrease in cash	$	(524)