Valuation and qualifying accounts (Tables)

12 Months Ended

Dec. 31, 2016

Valuation and qualifying accounts

Schedule of valuation and qualifying accounts

	Balance at		Additions		Changes to		Balance at
	beginning		charged to		reserve, net(1)		end of year
	of year		earnings
Year ended December 31, 2016
Allowance for doubtful accounts	$	1,343	$	208	$	(393)	$	1,158
Reserves for inventory		2,604		2,206		(1,677)		3,133
Valuation of deferred tax assets		647		-		(7)		640
Year ended December 31, 2015
Allowance for doubtful accounts	$	1,667	$	305	$	(629)	$	1,343
Reserves for inventory		2,452		2,251		(2,099)		2,604
Valuation of deferred tax assets		1,600		-		(953)		647
Year ended December 31, 2014
Allowance for doubtful accounts	$	1,051	$	577	$	39	$	1,667
Reserves for inventory		1,599		1,752		(899)		2,452
Valuation of deferred tax assets		1,395		-		205		1,600

(1) Increases (deductions) from the allowance for doubtful accounts equal accounts receivable written off and increases related to acquired businesses, less recoveries, against the allowance. Increases (deductions) from the reserves for inventory excess and obsolete items equal inventory written off against the reserve as items were disposed of and increases related to acquired businesses. Increases (deductions) to the valuation of deferred tax assets relate to the reversals due to changes in management’s judgments regarding the future realization of the underlying deferred tax assets.