Financial instruments (Tables)

12 Months Ended

Dec. 31, 2017

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Derivative Instruments in Statement of Financial Position, Fair Value

The following table presents the locations in the consolidated balance sheets and fair value of derivative instruments as of December 31, 2017 and 2016:



	December 31, 2017		December 31, 2016
	Fair Value
	(Dollars in thousands)
Asset derivatives:
Designated foreign currency forward contracts	$	914	$	667
Non-designated foreign currency forward contracts	307		490
Prepaid expenses and other current assets	1,221		1,157
Total asset derivatives	1,221		1,157
Liability derivatives:
Designated foreign currency forward contracts	1,373		2,139
Non-designated foreign currency forward contracts	53		118
Other current liabilities	1,426		2,257
Total liability derivatives	$	1,426	$	2,257

Aggregate Accounts Receivable, Net of Allowance for Doubtful Accounts

The aggregate net current and long-term trade accounts receivable for customers in Greece, Italy, Spain and Portugal and the percentage of the Company’s total net current and long-term trade accounts receivable represented by the net current and long-term trade accounts receivable for customers in those countries at December 31, 2017 and 2016 are as follows:



	December 31, 2017			December 31, 2016
	(Dollars in thousands)
Current and long-term trade accounts receivable in Greece, Italy, Spain and Portugal ⁽¹⁾	$	49,054		$	51,098
Percentage of total net current and long-term trade accounts receivables	14.6		%	19.3		%

(1) The long-term portion of trade accounts receivable, net from customers in Greece, Italy, Spain and Portugal at December 31, 2017 and 2016 was $3.3 million and $2.7 million, respectively. In January 2017, the Company sold $16.1 million of receivables outstanding with publicly funded hospitals in Italy for $16.0 million.