Accrued Liabilities

12 Months Ended

Dec. 31, 2013

Accrued Liabilities

Accrued Liabilities

(8) Accrued Liabilities

        Accrued liabilities at December 31, 2012 and 2013 consisted of the following:

	2012		2013
Salaries and wages	$	4,558	$	6,768
Accrued gas and equipment purchases		10,091		8,035
Derivative liability		112		—
Contingent consideration obligations		70		384
Accrued property and other taxes		4,483		5,448
Accrued professional fees		1,310		1,335
Accrued employee benefits		2,607		2,898
Accrued warranty liability		2,665		2,545
Accrued interest		302		4,216
Other		4,596		15,116
	$	30,794	$	46,745