Significant Customers - Additional Information (Details) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($) Customer	Dec. 31, 2017 USD ($) Customer	Dec. 31, 2016 USD ($) Customer
Segment Reporting Information [Line Items]
Accounts receivable, net	$ 81,313	$ 68,920
Number of major customer \| Customer	0	0	0
Customer Concentration Risk [Member] \| Sales Revenue, Services, Net [Member]
Segment Reporting Information [Line Items]
Revenue percent	100.00%	100.00%	100.00%
IBM [Member]
Segment Reporting Information [Line Items]
Revenue	$ 80,600	$ 76,400	$ 98,400
Extended period of services agreement	2 years
Services agreement expiration date	Dec. 31, 2019
Accounts receivable, net	$ 22,100	$ 21,500
IBM [Member] \| Customer Concentration Risk [Member] \| Sales Revenue, Services, Net [Member]
Segment Reporting Information [Line Items]
Revenue percent	22.50%	25.40%	30.30%
SDI [Member]
Segment Reporting Information [Line Items]
Revenue	$ 27,600	$ 34,200	$ 34,500
Accounts receivable, net	$ 3,600	$ 4,700
SDI [Member] \| Customer Concentration Risk [Member] \| Sales Revenue, Services, Net [Member]
Segment Reporting Information [Line Items]
Revenue percent	7.70%	11.40%	10.60%

Number of major customer.

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- Definition

Services agreement expiration date.

+ References

No definition available.

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- Definition

Services agreement maturity extended term.

+ References

No definition available.

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- Definition

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

+ References

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

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- Definition

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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