Refers to credit carryforwards refund period.

No definition available.

Name:	plab_CreditCarryforwardsRefundPeriod
Namespace Prefix:	plab_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	plab_EffectOfTaxCutsAndJobsActOf2017Abstract
Namespace Prefix:	plab_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of foreign federal statutory tax rate applicable to pretax income (loss).

+ References

No definition available.

+ Details

Name:	plab_EffectiveIncomeTaxRateReconciliationAtForeignStatutoryIncomeTaxRatePercent
Namespace Prefix:	plab_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations, attributable to increase (decrease) from transition tax on accumulated earnings in cash of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act of 2017.

+ References

No definition available.

+ Details

Name:	plab_EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017TransitionTaxOnAccumulatedForeignEarningsInCashPercent
Namespace Prefix:	plab_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of reported income tax expense (benefit) in excess of (less than) expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operations, attributable to increase (decrease) from transition tax on accumulated earnings not in cash of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act of 2017.

+ References

No definition available.

+ Details

Name:	plab_EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017TransitionTaxOnAccumulatedForeignEarningsNotInCashPercent
Namespace Prefix:	plab_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	plab_ForeignTaxAbstract
Namespace Prefix:	plab_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	plab_IncomeTaxHolidayAbstract
Namespace Prefix:	plab_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	plab_SignificantChangeInUnrecognizedTaxBenefitsReasonablyPossibleAbstract
Namespace Prefix:	plab_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	plab_TaxCreditCarryforwardAbstract
Namespace Prefix:	plab_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of reasonable estimate for income tax expense for remeasurement of deferred tax asset from change in tax rate pursuant to Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete.

+ References

No definition available.

+ Details

Name:	plab_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateDeferredTaxAssetProvisionalIncomeTaxExpense
Namespace Prefix:	plab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of reasonable estimate for valuation allowance for remeasurement of deferred tax asset from change in tax rate pursuant to Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete.

+ References

No definition available.

+ Details

Name:	plab_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateDeferredTaxAssetValuationAllowance
Namespace Prefix:	plab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of reasonable estimate for income tax expense (benefit) for remeasurement of deferred tax from change in tax rate pursuant to Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete.

+ References

No definition available.

+ Details

Name:	plab_TaxCutsAndJobsActOf2017IncompleteAccountingChangeInTaxRateProvisionalIncomeTaxExpenseBenefit
Namespace Prefix:	plab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of reasonable estimate for income tax expense from transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete.

+ References

No definition available.

+ Details

Name:	plab_TaxCutsAndJobsActOf2017IncompleteAccountingTransitionTaxForAccumulatedForeignEarningsProvisionalIncomeTaxExpense
Namespace Prefix:	plab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of reasonable estimate for valuation allowance from transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete.

+ References

No definition available.

+ Details

Name:	plab_TaxCutsAndJobsActOf2017IncompleteAccountingTransitionTaxForAccumulatedForeignEarningsValuationAllowance
Namespace Prefix:	plab_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Refers to term of tax year holidays.

+ References

No definition available.

+ Details

Name:	plab_TermOfTaxYearHolidays
Namespace Prefix:	plab_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (d)(3)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

+ Details

Name:	us-gaap_DecreaseInUnrecognizedTaxBenefitsIsReasonablyPossible
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(2))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

+ Details

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

- Definition

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I)
-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

+ Details

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

- Definition

Amount of income tax expense (benefit) from continuing operations attributable to an adjustment of a deferred tax liability or asset for enacted changes in tax laws or rates or a change in the tax status of the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32639-109319

+ Details

Name:	us-gaap_IncomeTaxExpenseBenefitContinuingOperationsAdjustmentOfDeferredTaxAssetLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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

- Definition

The amount of income taxes from which a reporting entity is exempt or for which it will receive a reduction in income taxes as a result of the income tax holiday granted by the taxing jurisdiction.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330215-122817

+ Details

Name:	us-gaap_IncomeTaxHolidayAggregateDollarAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Per share amount effect of the income tax benefit resulting from the income tax holidays granted by taxing jurisdictions.

+ References

+ Details

Name:	us-gaap_IncomeTaxHolidayIncomeTaxBenefitsPerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The date on which the special tax status will terminate.

+ References

+ Details

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

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Definition

The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32559-109319

+ Details

Name:	us-gaap_TaxCreditCarryforwardAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 10B
-URI http://asc.fasb.org/extlink&oid=84176650&loc=SL37586934-109318

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=SL6600010-109319

+ Details

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

- Definition

Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32718-109319

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e32123-109318

+ Details

Name:	us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_IncomeTaxAuthorityNameAxis=plab_TaiwanAgencyOfTheMinistryOfFinanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TaxCreditCarryforwardAxis=plab_AlternateMinimumTaxCreditCarryforwardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementScenarioAxis=us-gaap_ScenarioPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeTaxAuthorityAxis=us-gaap_ForeignCountryMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

INCOME TAXES (Details) - USD ($) $ / shares in Units, $ in Millions	2 Months Ended	3 Months Ended			7 Months Ended	9 Months Ended		12 Months Ended
	Dec. 31, 2017	Jul. 29, 2018	Jan. 28, 2018	Jul. 30, 2017	Jul. 29, 2018	Jul. 29, 2018	Jul. 30, 2017	Oct. 27, 2019	Oct. 28, 2018	Oct. 29, 2017
Effective Income and Statutory Tax Rate [Abstract]
Effective tax rate		9.40%		6.50%		7.80%	20.70%
U.S. statutory rate	35.00%			35.00%	21.00%
Effect of Tax Cuts and Jobs Act of 2017 [Abstract]
Change in tax rate, deferred tax asset, provisional income tax expense						$ (2.5)
Change in tax rate, deferred tax asset, valuation allowance						$ 2.5
Toll charge rate on accumulated earnings in cash						15.50%
Toll charge rate on accumulated earnings not in cash						8.00%
Estimated deemed repatriation transition tax						$ 28.4
Estimated deemed repatriation transition tax, valuation allowance						(28.4)
Provisional income tax expense (benefit)						$ 0.0
Income Tax Holiday [Abstract]
Term of tax year holidays						5 years
Dollar effect of income tax holiday		$ 1.1		$ 0.1		$ 1.8	$ 0.2
Per share effect of income tax holiday (in dollars per share)		$ 0.1		$ 0		$ 0.2	$ 0
Unrecognized Tax Benefits [Abstract]
Unrecognized tax benefits		$ 1.5			$ 1.5	$ 1.5				$ 3.4
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued [Abstract]
Interest and penalties accrued related to uncertain tax positions		0.1			0.1	0.1				$ 0.1
Significant Change in Unrecognized Tax Benefits Reasonably Possible [Abstract]
Amount of reasonably possible decrease in uncertain tax positions		$ 0.6			$ 0.6	$ 0.6
Taiwan Agency of the Ministry of Finance [Member]
Foreign Tax [Abstract]
Foreign statutory rate						20.00%				17.00%
Foreign income tax expense (benefit)			$ (0.2)
Federal Alternate Minimum [Member]
Tax Credit Carryforward [Abstract]
Credit carryforwards refund period						4 years
Tax credit carryforward, amount			$ 3.9
Valuation allowance change						$ (3.7)
Plan [Member]
Effective Income and Statutory Tax Rate [Abstract]
U.S. statutory rate								21.00%	23.40%
Foreign Tax Authority [Member] \| Minimum [Member]
Income Tax Holiday [Abstract]
Income tax holiday termination date						October 31, 2017
Foreign Tax Authority [Member] \| Maximum [Member]
Income Tax Holiday [Abstract]
Income tax holiday termination date						December 31, 2019