Commitments and Contingencies (Narrative) (Details) $ in Millions	6 Months Ended
Jun. 30, 2017 USD ($)
Commitments and Contingencies
Probable future cost for envionmental remediation	$ 1
Entity Number of Employees	37,000
Surety Bonds Outstanding
Commitments and Contingencies
Surety bonds outstanding	$ 258
HII Credit Facility \| Letters of Credit
Commitments and Contingencies
Letters of credit issued but undrawn	$ 15
Minimum
Commitments and Contingencies
Period Covered by Collective Bargaining Agreements	3 years
Maximum
Commitments and Contingencies
Period Covered by Collective Bargaining Agreements	5 years
Number of Collective Bargaining Unit, Total [Member]
Commitments and Contingencies
Concentration Risk, Labor Subject to Collective Bargaining Arrangements	9
Workforce Subject To Collective Bargaining Arrangements, Percent [Member]
Commitments and Contingencies
Concentration Risk, Labor Subject to Collective Bargaining Arrangements	0.5
Number of Collective Bargaining Unit, Newport News [Member]
Commitments and Contingencies
Concentration Risk, Labor Subject to Collective Bargaining Arrangements	4
Number of Collective Bargaining Unit, Pascagoula and Gulfport [Member]
Commitments and Contingencies
Concentration Risk, Labor Subject to Collective Bargaining Arrangements	5
Hanford Site, Richland, Washington [Member]
Commitments and Contingencies
Entity Number of Employees	35
United Steelworkers [Member] \| Newport News \| Workforce Subject To Collective Bargaining Arrangements, Percent [Member]
Commitments and Contingencies
Concentration Risk, Labor Subject to Collective Bargaining Arrangements	0.5

Number of persons employed by the Entity

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Description of the significant collective-bargaining arrangements within the range of expiration dates for collective-bargaining arrangements as well as other information to help investors understand the significance of the collective-bargaining agreements and when they expire.

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Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable in twelve months or in the next operating cycle if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 50
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Description of any concentration of labor subject to collective bargaining agreements, including the general nature of the risk.

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The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

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

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