Business Acquisition (Unaudited) (Details 3) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2018 USD ($) $ / shares
Business Acquisition [Line Items]
Pro forma sales	$ 8,000
Pro forma net earnings	$ 914
Pro forma diluted earnings per share \| $ / shares	$ 5.21
Pro Forma Adjustments, Orbital ATK intercompany sales elimination	$ (47)
Pro Forma Adjustments, Elimination of nonrecurring transaction costs	7
Pro Forma Adjustments, Additional depreciation expense, net of removal of historical depreciation	(6)
Pro Forma Adjustments, Additional amortization expense, net of removal of historical amortization expense	(66)
Pro Forma Adjustments, Elimination of Orbital ATK’s amortization on net actuarial losses and prior service costs and pension/post-retirement costs	31
Income Tax Effects of Pro Forma Adjustments	$ 7

Income Tax Effects of Pro Forma Adjustments

No definition available.

Name:	noc_IncomeTaxEffectsofProFormaAdjustments
Namespace Prefix:	noc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Pro Forma Adjustments, Additional amortization expense, net of removal of historical amortization expense

+ References

No definition available.

+ Details

Name:	noc_ProFormaAdjustmentsAdditionalamortizationexpensenetofremovalofhistoricalamortizationexpense
Namespace Prefix:	noc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Pro Forma Adjustments, Additional depreciation expense, net of removal of historical depreciation

+ References

No definition available.

+ Details

Name:	noc_ProFormaAdjustmentsAdditionaldepreciationexpensenetofremovalofhistoricaldepreciation
Namespace Prefix:	noc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Pro Forma Adjustments, Elimination of Orbital ATK’s historical amortization of net actuarial losses and prior service credits and revised pension and other post-retirement costs

+ References

No definition available.

+ Details

Name:	noc_ProFormaAdjustmentsEliminationofOrbitalATKshistoricalamortizationofnetactuariallossesandpriorservicecreditsandrevisedpensionandotherpostretirementcosts
Namespace Prefix:	noc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Business combination, transaction costs

+ References

No definition available.

+ Details

Name:	noc_ProFormaAdjustmentsEliminationofnonrecurringtransactioncosts
Namespace Prefix:	noc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Pro Forma Adjustments, Orbital ATK intercompany sales elimination

+ References

No definition available.

+ Details

Name:	noc_ProFormaAdjustmentsOrbitalATKintercompanysaleselimination
Namespace Prefix:	noc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- 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.

+ Details

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

- 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

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

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

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

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

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(2)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(3)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

+ Details

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