Goodwill and other intangibles - Additional Information (Details) $ in Thousands	9 Months Ended
Sep. 30, 2018 USD ($)
Business Acquisition [Line Items]
Increase in goodwill	$ 15,804
Intangibles recorded in connection with acquisitions	$ 4,400
Acquired software \| Minimum
Business Acquisition [Line Items]
Acquired intangibles, amortization period	1 year
Acquired software \| Maximum
Business Acquisition [Line Items]
Acquired intangibles, amortization period	3 years
Title
Business Acquisition [Line Items]
Increase in goodwill	$ 15,804

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
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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

The amount of identifiable intangible assets recognized as of the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 55
-Paragraph 37
-URI http://asc.fasb.org/extlink&oid=108330185&loc=d3e2207-128464

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- Definition

Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267

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