Information on Business Segments - FAS/CAS Pension Adjustment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Non-operating FAS pension income (expense)	$ 219	$ (577)	$ (801)
Net FAS/CAS pension adjustment	2,095	1,472	1,002
Segment Reconciling Items
Segment Reporting Information [Line Items]
FAS pension service cost	(101)	(516)	(630)
Less: CAS pension cost	1,977	2,565	2,433
FAS/CAS operating adjustment	1,876	2,049	1,803
Qualified Defined Benefit Pension Plans
Segment Reporting Information [Line Items]
FAS pension income (expense)	(118)	1,093	1,431
FAS pension service cost	(101)	(516)	(630)
Qualified Plan | Qualified Defined Benefit Pension Plans
Segment Reporting Information [Line Items]
FAS pension income (expense)	$ 118	$ (1,093)	$ (1,431)