Allowable business interest deduction percentage of adjusted taxable income.

No definition available.

Name:	psn_AllowableBusinessInterestDeductionPercentageOfAdjustedTaxableIncome
Namespace Prefix:	psn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Income taxes.

+ References

No definition available.

+ Details

Name:	psn_IncomeTaxesLineItems
Namespace Prefix:	psn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating loss carryforwards description.

+ References

No definition available.

+ Details

Name:	psn_OperatingLossCarryforwardsDescription
Namespace Prefix:	psn_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of net operating loss carryforwards to offset of taxable income during a period.

+ References

No definition available.

+ Details

Name:	psn_PercentageOfNetOperatingLossCarryforwardsToOffsetOfTaxableIncomeDuringPeriod
Namespace Prefix:	psn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32537-109319

+ Details

Name:	us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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=116825942&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 recognized for uncertainty in income taxes classified as current.

+ 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 210.5-02.20)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Details

Name:	us-gaap_StatutoryAccountingPracticesByJurisdictionAxis=psn_CoronavirusAidReliefAndEconomicSecurityActMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Income Taxes - Additional Information (Details) - USD ($) $ in Millions		3 Months Ended
	Mar. 27, 2020	Mar. 31, 2020	Mar. 31, 2019	Mar. 26, 2020	Dec. 31, 2019
Income Taxes [Line Items]
Effective income tax rate		26.13%	12.35%
U.S. corporate tax rate		21.00%
Deferred tax assets valuation allowance		$ 18.2
Liability for income taxes associated with uncertain tax positions		$ 14.8			$ 15.5
CARES Act
Income Taxes [Line Items]
Percentage of net operating loss (NOL) carryovers to offset of taxable income	100.00%
Allowable business interest deduction percentage of adjusted taxable income	50.00%			30.00%
Operating loss carryforwards description		In addition, the CARES Act allows NOLs incurred in 2018, 2019, and 2020 to be carried back to each of the five preceding tax years to generate a refund of previously paid income taxes.