CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Allocated share-based compensation expense	$ 15,111	$ 8,540
Amortization of acquisition intangible assets	1,025	1,092
Cost of revenue
Allocated share-based compensation expense	1,096	658
Amortization of acquisition intangible assets	488	488
Research and development
Allocated share-based compensation expense	4,766	3,447
Sales and marketing
Allocated share-based compensation expense	2,780	768
Amortization of acquisition intangible assets	537	604
General and administrative
Allocated share-based compensation expense	$ 6,469	$ 3,667

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16323-109275

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16225-109274

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