OPERATING SEGMENTS, Reconciliation of Segment Revenues and Operating Profit to Consolidated Income From Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 200,045us-gaap_Revenues	$ 160,384us-gaap_Revenues
Segment Reporting Information [Line Items]
Income from operations	22,820us-gaap_OperatingIncomeLoss	21,857us-gaap_OperatingIncomeLoss
Stock-based compensation expense	(9,134)us-gaap_ShareBasedCompensation	(3,208)us-gaap_ShareBasedCompensation
Depreciation and amortization	(4,200)us-gaap_DepreciationAndAmortization	(3,689)us-gaap_DepreciationAndAmortization
Interest and other income, net	1,158us-gaap_InvestmentIncomeNet	976us-gaap_InvestmentIncomeNet
Foreign exchange loss	(5,754)	(1,241)
Income before provision for income taxes	18,224	21,592
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	200,194	159,997
Segment Reporting Information [Line Items]
Income from operations	38,680	29,879
Unallocated Amounts
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(149)	387
Segment Reporting Information [Line Items]
Other revenues	(149)	387
Stock-based compensation expense	(9,134)	(3,208)
Non-corporate taxes	(825)	(546)
Professional fees	(1,822)	(1,314)
Depreciation and amortization	(1,329)	(655)
Bank charges	(367)	(247)
Other corporate expenses	$ (2,234)	$ (2,439)

Bank Service Charge

No definition available.

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- Definition

The current period expense charged against earnings on long-lived, physical assets not used in production, and which are not intended for resale, to allocate or recognize the cost of such assets over their useful lives; or to record the reduction in book value of an intangible asset over the benefit period of such asset; or to reflect consumption during the period of an asset that is not used in production.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

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- Definition

Amount before tax of foreign currency transaction realized and unrealized gain (loss) recognized in the income statement.

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-Publisher FASB

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- Definition

Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest.

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-Publisher FASB

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- Definition

Amount after accretion (amortization) of discount (premium), and investment expense, of interest income and dividend income on nonoperating securities.

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

No definition available.

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- Definition

This element represents a sum total of expenses not separately reflected on the income statement for the period.

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-Name Accounting Standards Codification

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- Definition

Revenues from the sale of other goods or rendering of other services, not elsewhere specified in the taxonomy; net of (reduced by) sales adjustments, returns, allowances, and discounts.

+ References

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- Definition

A fee charged for services from professionals such as doctors, lawyers and accountants. The term is often expanded to include other professions, for example, pharmacists charging to maintain a medicinal profile of a client or customer.

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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

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- Definition

The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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- Definition

Taxes, excluding payroll, income and excise taxes, if not included elsewhere, that could include production, real and personal property, and other selling and distribution-related taxes.

+ References

No definition available.

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