Business Combinations, Pro Forma Results of Operations (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Business Acquisition, Pro Forma Information [Abstract]
Revenues	$ 111,019	$ 127,397
Net income	$ 3,268	$ 5,106
Basic net income per share	$ 0.10	$ 0.15
Diluted net income per share	$ 0.10	$ 0.15
Shares used in computing basic net income per share	33,385	33,971
Shares used in computing diluted net income per share	34,299	34,989

Business acquisition proforma weighted average shares outstanding basic.

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- Definition

Business acquisition proforma weighted average shares outstanding diluted.

+ References

No definition available.

+ Details

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Namespace Prefix:	prft_
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- Definition

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)-(3)
-URI http://asc.fasb.org/extlink&oid=65885119&loc=d3e1392-128463

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- Definition

The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

+ References

+ Details

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- References

No definition available.

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- Definition

The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

+ References

+ Details

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- Definition

The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

+ References

+ Details

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