OTHER - Changes in Estimates (Details) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Feb. 29, 2020 satellite	Sep. 27, 2020 USD ($) $ / shares	Sep. 29, 2019 USD ($) $ / shares	Sep. 27, 2020 USD ($) satellite $ / shares	Sep. 29, 2019 USD ($) $ / shares	Dec. 31, 2019 satellite
Change in Accounting Estimate [Line Items]
Performance obligation satisfied in previous period		$ 487	$ 495	$ 1,500	$ 1,700
Number of satellites launched or to be launched | satellite	1			3		2
Space
Change in Accounting Estimate [Line Items]
Number of commercial satellite programs with performance issues | satellite						2
Ground Based Radar
Change in Accounting Estimate [Line Items]
Cumulative losses on development		250		$ 250
EADGE-T
Change in Accounting Estimate [Line Items]
Cumulative losses on development		260		260
LM 2100 Project
Change in Accounting Estimate [Line Items]
Cumulative losses on development		410		410
Warrior Capability Sustainment Program
Change in Accounting Estimate [Line Items]
Cumulative losses on development		140		140
Contracts Accounted for under Percentage of Completion
Change in Accounting Estimate [Line Items]
Increase in operating profit due to profit rate adjustments		415	480	1,400	1,500
Increase in net earnings due to profit rate adjustments		$ 328	$ 379	$ 1,100	$ 1,200
Increase in diluted earnings per common share due to profit rate adjustments (in dollars per share) | $ / shares		$ 1.17	$ 1.33	$ 3.82	$ 4.07