Long-term Debt - Revolving Credit Facility (Details) - USD ($)	9 Months Ended
Sep. 30, 2020	Dec. 31, 2019
Line of Credit [Abstract]
Leverage Ratio	3.00
Long-term debt, net	$ 187,737,000	$ 124,664,000
Revolving credit facility \| London interbank offered rate (LIBOR) \| Minimum
Line of Credit [Abstract]
Margin interest rate percentage	1.00%
Revolving credit facility \| London interbank offered rate (LIBOR) \| Maximum
Line of Credit [Abstract]
Margin interest rate percentage	1.75%
Revolving credit facility \| Credit agreement
Line of Credit [Abstract]
Maximum borrowing capacity	$ 125,000,000.0
Additional commitment increase	$ 75,000,000.0
Maturity date	Jun. 09, 2022
Allowable amount of letters of credit for issuance	$ 10,000,000.0
Letters of credit outstanding	200,000
Available borrowing capacity	$ 124,800,000
EBITDA Ratio	3.00
Leverage Ratio needed for payment of dividends	2.00
Revolving credit facility \| Credit agreement \| Minimum
Line of Credit [Abstract]
Annual commitment fee percentage on unused capacity	0.15%
Revolving credit facility \| Credit agreement \| Maximum
Line of Credit [Abstract]
Annual commitment fee percentage on unused capacity	0.20%
Revolving credit facility \| Credit agreement \| Prime rate
Line of Credit [Abstract]
Interest rate at end of period	3.25%
Revolving credit facility \| Credit agreement \| Prime rate \| Minimum
Line of Credit [Abstract]
Margin interest rate percentage	0.00%
Revolving credit facility \| Credit agreement \| Prime rate \| Maximum
Line of Credit [Abstract]
Margin interest rate percentage	0.50%
Revolving credit facility \| Credit agreement \| London interbank offered rate (LIBOR)
Line of Credit [Abstract]
Interest rate at end of period	0.15%

Amount of additional commitment increase on the credit facility.

No definition available.

Name:	prft_LineOfCreditFacilityAdditionalCommitmentIncrease
Namespace Prefix:	prft_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Allowable amount for issuance of letters of credit under the credit facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	prft_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Ratio of earnings before interest, taxes, depreciation, and amortization (EBITDA) plus stock compensation to interest expense for the previous four consecutive fiscal quarters.

+ References

No definition available.

+ Details

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Namespace Prefix:	prft_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Ratio of indebtedness to EBITDA plus stock compensation (Leverage Ratio).

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Ratio of indebtedness to EBITDA plus stock compensation (Leverage Ratio) needed for payment of dividends.

+ References

No definition available.

+ Details

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Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate at the end of the reporting period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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- Details

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- Details

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- Details

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