Investments (Details 1) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	$ 45,676	$ 28,869
Gross Unrealized Gains	531	844
Gross Unrealized Losses	(571)	(121)
Fair Value	45,636	29,592
Certificates of deposit (non-U.S.)
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	39,640	12,809
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	39,640	12,809
Corporate bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	0	11,003
Gross Unrealized Gains	0	86
Gross Unrealized Losses	0	(24)
Fair Value	0	11,065
Corporate obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	14	13
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	14	13
Money markets
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	37	38
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	37	38
Mutual funds
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	87	65
Gross Unrealized Gains	0	14
Gross Unrealized Losses	(1)	0
Fair Value	86	79
Other investments
Debt Securities, Available-for-sale [Line Items]
Amortized Costs	5,898	4,941
Gross Unrealized Gains	531	744
Gross Unrealized Losses	(570)	(97)
Fair Value	$ 5,859	$ 5,588

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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