Commitments and Contingent Liabilities - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Operating lease expiration description		The facilities of the Company are leased under various operating lease agreements for periods ending no later than 2024.
Pledged bank deposits		$ 1,145	$ 1,038
Operating lease and other contractual commitments		1,305	$ 1,202
Settlement agreement date	February 10, 2015
Settlement Agreement
Loss Contingencies [Line Items]
Settlement expense	$ 5,500
Net sales milestone		$ 250,000
Motor Vehicles
Loss Contingencies [Line Items]
Operating lease expiration description		The Company also leases motor vehicles under various operating leases, which expire on various dates, the latest of which is in 2021.
Maximum
Loss Contingencies [Line Items]
Operating lease agreements, expiration year		2024
Maximum | Motor Vehicles
Loss Contingencies [Line Items]
Operating lease agreements, expiration year		2021