Postretirement Benefit Plans - Reconciliation of Benefit Obligations, Plan Assets, and Unfunded or Funded Status (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Change in plan assets
Beginning balance at fair value	$ 33,204
Ending balance at fair value	34,978	$ 33,204
Qualified Defined Benefit Pension Plans
Change in benefit obligation
Beginning balance	45,064	43,702
Service cost	820	827	$ 836
Interest cost	1,809	1,861	1,791
Benefits paid	(2,310)	(2,172)
Actuarial losses (gains)	3,377	1,402
Changes in longevity assumptions	(352)	(687)
Plan amendments and acquisitions	278	110
Service cost related to discontinued operations	0	21
Medicare Part D subsidy	0	0
Participants’ contributions	0	0
Ending balance	48,686	45,064	43,702
Change in plan assets
Beginning balance at fair value	31,417	32,096
Actual return on plan assets	3,942	1,470
Benefits paid	(2,310)	(2,172)
Company contributions	0
Medicare Part D subsidy	0	0
Participants’ contributions	0	0
Ending balance at fair value	33,095	31,417	32,096
Unfunded status of the plans	(15,591)	(13,647)
Qualified Defined Benefit Pension Plans \| Information Systems & Global Solutions
Change in plan assets
Special termination benefits		27
Retiree Medical and Life Insurance Plans
Change in benefit obligation
Beginning balance	2,649	2,883
Service cost	20	24	21
Interest cost	102	119	110
Benefits paid	(232)	(222)
Actuarial losses (gains)	23	(135)
Changes in longevity assumptions	(24)	(53)
Plan amendments and acquisitions	0	(32)
Service cost related to discontinued operations	0	0
Medicare Part D subsidy	0	4
Participants’ contributions	64	61
Ending balance	2,602	2,649	2,883
Change in plan assets
Beginning balance at fair value	1,787	1,813
Actual return on plan assets	224	95
Benefits paid	(232)	(222)
Company contributions	40	36
Medicare Part D subsidy	0	4
Participants’ contributions	64	61
Ending balance at fair value	1,883	1,787	$ 1,813
Unfunded status of the plans	(719)	(862)
Retiree Medical and Life Insurance Plans \| Information Systems & Global Solutions
Change in plan assets
Special termination benefits		9
Sikorsky Aircraft Corporation \| Qualified Defined Benefit Pension Plans
Change in plan assets
Company contributions	$ 46	$ 23

Amount of increase in benefit obligation resulting from a change in the longevity (also known as mortality) assumption.

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- Definition

Defined Benefit Plan, Plan Amendments and Acquisitions

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- Definition

Defined Benefit Plan Service Cost Related To Discontinued Operations

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- Definition

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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- Definition

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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- Definition

Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964

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-Publisher FASB
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- Definition

Amount of contributions received by defined benefit plan from participant which increase benefit obligation.

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- Definition

Amount, before benefit payment, of receipt from prescription drug subsidy which increases benefit obligation of defined benefit postretirement plan.

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- Definition

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

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No definition available.

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

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
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-Publisher FASB
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-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees.

+ References

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- Definition

Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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- Definition

Amount of cost recognized for passage of time related to defined benefit plan.

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- Definition

Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 60
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39716-114964

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-Publisher FASB
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Amount of contributions received by defined benefit plan from participant which increases plan assets.

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- Definition

Amount of receipt from prescription drug subsidy which increases plan assets of defined benefit postretirement plan.

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- Definition

Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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- Definition

Amount of increase in benefit obligation for benefits provided to employees payable from defined benefit plan or payable upon retirement.

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