Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Portion Not Accrued	$ 1,059		$ 1,095
Letters of Credit Outstanding, Amount	4,037		4,238
737 MAX customer concessions and other considerations liability	4,400
Contingent On Customer Negotiations
Commitments And Contingencies [Line Items]
737 MAX customer concessions and other considerations liability	1,900
Lower Customer Delivery Payments
Commitments And Contingencies [Line Items]
737 MAX customer concessions and other considerations liability	1,700
Cash Payments To Customers
Commitments And Contingencies [Line Items]
737 MAX customer concessions and other considerations liability	600
Customer Concessions
Commitments And Contingencies [Line Items]
737 MAX customer concessions and other considerations liability	200
Within Current fiscal Year [Member]
Commitments And Contingencies [Line Items]
737 MAX customer concessions and other considerations liability	300
Within Next fiscal Year [Member]
Commitments And Contingencies [Line Items]
Abnormal Production cost.	5,000
737 MAX customer concessions and other considerations liability	300
Financing Commitment
Commitments And Contingencies [Line Items]
Other Commitment	13,383		11,512
Joint venture
Commitments And Contingencies [Line Items]
Other Commitment	243
Total Contractual Trade-In Commitment | Commercial Aircraft Commitments
Commitments And Contingencies [Line Items]
Other Commitment	623		950
Net Amounts Payable to Customers Related to Probable Contractual Trade-In Commitments | Commercial Aircraft Commitments
Commitments And Contingencies [Line Items]
Other Commitment	400		599
Fair Value of Trade In Value of Aircraft | Commercial Aircraft Commitments
Commitments And Contingencies [Line Items]
Other Commitment	400		580
KC-46A Tanker
Commitments And Contingencies [Line Items]
Contract Value	19,000
KC-46A Tanker | Capitalized Precontract Costs
Commitments And Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss	268
KC-46A Tanker | Potential Termination Liabilities
Commitments And Contingencies [Line Items]
Loss Contingency, Estimate of Possible Loss	180
B-737
Commitments And Contingencies [Line Items]
Abnormal Production cost.	568		2,567
737 MAX customer concessions and other considerations liability	4,370	$ 6,686	$ 5,537	$ 7,389
737 MAX Storage, Pilot Training and Software Updates [Member]
Commitments And Contingencies [Line Items]
Additional expenses as a result of the 737 MAX grounding	$ 53	$ 61