New Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	$ 747,950	$ 520,753	$ 450,557
Cost of revenue	168,698	115,590	102,571
Gross margin	$ 579,252	$ 405,163	$ 347,986
Gross margin percent	77.00%	78.00%	77.00%
Adjustment to revenue
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	$ 18,133	$ 8,762	$ 20,434
Cost of revenue	18,591	15,480	20,514
Gross margin	$ (458)	$ (6,718)	$ (80)
Gross margin percent	(1.00%)	(3.00%)	(3.00%)
Revenue as restated
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenue	$ 766,083	$ 529,515	$ 470,991
Cost of revenue	187,289	131,070	123,085
Gross margin	$ 578,794	$ 398,445	$ 347,906
Gross margin percent	76.00%	75.00%	74.00%

Gross Profit Percent

No definition available.

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- Definition

The aggregate costs related to goods produced and sold and services rendered by an entity during the reporting period. This excludes costs incurred during the reporting period related to financial services rendered and other revenue generating activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(a),(d))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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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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- Definition

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1,2)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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