Other Current Assets

12 Months Ended

Dec. 31, 2016

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Other Current Assets

Other Current Assets

The following table shows the breakdown in other current assets net book value for the presented periods:  

	Year Ended December 31,
	2015		2016
	(in thousands)
Prepayments to suppliers	$	2,774	$	2,439
Employee-related receivables	94		97
Taxes receivables	29,552		52,942
Other debtors	3,687		3,166
Prepaid expenses	9,475		13,638
Gross book value at end of period	45,582		72,282
Net book value at end of period	$	45,582	$	72,282

Taxes receivables are primarily composed of VAT receivables and research tax credit receivables. Prepaid expenses mainly consist of office rental advance payments.