Commitments, Rights of Use and Contingent Liabilities - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
Operating lease expiration description	The facilities of the Company are leased under various operating lease agreements for periods, including options for extensions, ending no later than 2029.
Operating lease, extistence of option to extend	true
Increase in right-of-use assets obtained in exchange for lease obligations	$ 15,733
Lease and rental payments	1,740
Deferred rent	863
Pledged bank deposits	1,134	$ 1,143
Operating lease and other contractual commitments	$ 1,294	$ 1,299
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 2022.
Maximum
Loss Contingencies [Line Items]
Operating lease agreements, expiration year	2029
Maximum \| Motor Vehicles
Loss Contingencies [Line Items]
Operating lease agreements, expiration year	2022

Operating lease agreement expiration period.

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Operating lease expiration description.

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Amount of contractual obligation, including but not limited to, long-term debt, capital lease obligations, operating lease obligations, purchase obligations, and other commitments.

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For a classified balance sheet, the cumulative difference between the rental income or payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense, by the lessor or lessee, respectively, more than one year after the balance sheet date. Such receivable is reduced by allowances attributable to, for instance, credit risk associated with a lessee.

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Carrying value of amounts transferred to third parties for security purposes that are expected to be returned or applied towards payment in the future.

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Indicates (true false) whether lessee has option to extend operating lease.

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Amount of operating lease expense. Excludes sublease income.

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Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

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