Schedule of Long-term debt (Table) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt	$ 2,276	$ 1,286
Less unamortized debt issuance costs	(29)	(19)
Senior Notes
Debt Instrument [Line Items]
Less unamortized debt issuance costs	(22)	(12)
Senior Notes \| Senior Notes Due November 15, 2025, 5.000%
Debt Instrument [Line Items]
Long-term debt	$ 600	$ 600
Debt Instrument, Interest Rate, Stated Percentage	5.00%	5.00%
Senior Notes \| Senior notes due December 1, 2027, 3.483% [Member]
Debt Instrument [Line Items]
Long-term debt	$ 600	$ 600
Debt Instrument, Interest Rate, Stated Percentage	3.483%	3.483%
Senior Notes \| Senior notes due May 1, 2025, 3.844% [Member]
Debt Instrument [Line Items]
Long-term debt	$ 500
Debt Instrument, Interest Rate, Stated Percentage	3.844%
Senior Notes \| Senior notes due May 1, 2030, 4.200%
Debt Instrument [Line Items]
Long-term debt	$ 500
Debt Instrument, Interest Rate, Stated Percentage	4.20%
Bonds \| Mississippi Economic Development Revenue Bonds Due May 1, 2024, 7.81%
Debt Instrument [Line Items]
Long-term debt	$ 84	$ 84
Debt Instrument, Interest Rate, Stated Percentage	7.81%	7.81%
Bonds \| Gulf Opportunity Zone Industrial Development Revenue Bonds Due December 1, 2028, 4.55%
Debt Instrument [Line Items]
Long-term debt	$ 21	$ 21
Debt Instrument, Interest Rate, Stated Percentage	4.55%	4.55%

Contractual interest rate for funds borrowed, under the debt agreement.

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 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- 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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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=109500613&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=119400593&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=6876686&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=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ 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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=hii_SeniorNotesDueNovember1520255.000Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=hii_SeniornotesdueDecember120273.483Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=hii_SeniorNotesDueMay120253844Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=hii_SeniorNotesDueMay120304200Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_BondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=hii_MississippiEconomicDevelopmentRevenueBondsDueMay120247.81PercentMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=hii_GulfOpportunityZoneIndustrialDevelopmentRevenueBondsDueDecember12028455PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: