Significant Accounting Policies - Additional Information (Detail)	1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 31, 2020 USD ($) $ / shares	Jun. 28, 2020 USD ($)	Dec. 31, 2020 USD ($) contract $ / shares	Dec. 31, 2019 USD ($) $ / shares	Dec. 31, 2018 USD ($) $ / shares
Significant Accounting Policies [Line Items]
Number of contract types | contract			3
Ending backlog			$ 147,100,000,000
Performance obligation satisfied in previous period			2,000,000,000.0	$ 2,200,000,000	$ 2,000,000,000.0
Independent research and development costs charged to cost of sales			$ 1,300,000,000	1,300,000,000	1,300,000,000
Weighted average remaining contractual life, vested			3 years
Depreciation			$ 853,000,000	794,000,000	759,000,000
Capitalized internal-use software, net			686,000,000	511,000,000
Capitalized internal-use software accumulated amortization			2,200,000,000	2,200,000,000
Capitalized internal-use software amortization			166,000,000	111,000,000	106,000,000
Goodwill			$ 10,806,000,000	10,604,000,000	10,769,000,000
Time period environmental costs and recovery of environmental costs are projected over			20 years
Fair value of trading securities			$ 2,000,000,000.0	1,800,000,000
Net gains (losses) on marketable securities			231,000,000	233,000,000	(67,000,000)
Total equity method investments			784,000,000	1,200,000,000
Net earnings from equity method investments			163,000,000	154,000,000	119,000,000
Equity method investee impairment			128,000,000	0	0
Interest rate swaps | Designated as hedges
Significant Accounting Policies [Line Items]
Aggregate notional amount of derivatives			572,000,000	750,000,000
Foreign currency contracts | Designated as hedges
Significant Accounting Policies [Line Items]
Aggregate notional amount of derivatives			3,400,000,000	3,800,000,000
AMMROC
Significant Accounting Policies [Line Items]
Total equity method investments	$ 307,000,000
Proceeds from sale of equity method investments	307,000,000
Equity method investee impairment	128,000,000	$ 128,000,000			110,000,000
Equity method investee impairment, net of tax	$ 96,000,000
Equity method investee impairment (in dollars per share) | $ / shares	$ 0.34
Space
Significant Accounting Policies [Line Items]
Goodwill			1,760,000,000	1,586,000,000	1,585,000,000
Net earnings from equity method investments			$ 135,000,000	145,000,000	210,000,000
Minimum
Significant Accounting Policies [Line Items]
Acquired finite-lived intangible assets are amortized			3 years
Minimum | Customer programs
Significant Accounting Policies [Line Items]
Acquired finite-lived intangible assets are amortized			9 years
Minimum | Buildings
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated life			10 years
Minimum | Machinery and equipment
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated life			5 years
Minimum | Capitalized Software
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated life			2 years
Maximum
Significant Accounting Policies [Line Items]
Acquired finite-lived intangible assets are amortized			20 years
Maximum | Customer programs
Significant Accounting Policies [Line Items]
Acquired finite-lived intangible assets are amortized			20 years
Maximum | Buildings
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated life			40 years
Maximum | Machinery and equipment
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated life			15 years
Maximum | Capitalized Software
Significant Accounting Policies [Line Items]
Property, plant and equipment, estimated life			6 years
Ground Based Radar
Significant Accounting Policies [Line Items]
Commercial satellite cumulative losses on development			$ 250,000,000
EADGE-T
Significant Accounting Policies [Line Items]
Commercial satellite cumulative losses on development			260,000,000
Warrior Capability Sustainment Program
Significant Accounting Policies [Line Items]
Commercial satellite cumulative losses on development			$ 140,000,000
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Over the next 12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage			39.00%
Expected time of satisfaction			12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Over the next 24 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, percentage			61.00%
Expected time of satisfaction			24 months
Contracts Accounted for under Percentage of Completion
Significant Accounting Policies [Line Items]
Increase in operating profit due to profit rate adjustments			$ 1,800,000,000	1,900,000,000	1,900,000,000
Increase in net earnings due to profit rate adjustments			$ 1,500,000,000	$ 1,500,000,000	$ 1,500,000,000
Increase in diluted earnings per common share due to profit rate (in dollars per share) | $ / shares			$ 5.33	$ 5.29	$ 5.23