Acquisitions and Divestitures, Goodwill, and Intangible Assets (Fair Value of Assets Acquired and Liabilities Assumed) (Details) - USD ($) $ in Millions	Dec. 31, 2020	[1]	Dec. 31, 2019	[2],[3]	Dec. 31, 2018	[3]	Apr. 03, 2018
Business Acquisition [Line Items]
Goodwill	$ 20,053		$ 19,677		$ 19,594
CSRA
Business Acquisition [Line Items]
Cash and equivalents							$ 45
Accounts receivable							155
Unbilled receivables							415
Other current assets							303
Property, plant and equipment, net							326
Intangible assets, net							2,066
Goodwill							7,935
Other noncurrent assets							369
Total assets							11,614
Accounts payable							(135)
Customer advances and deposits							(151)
Current lease obligation							(51)
Other current liabilities							(434)
Noncurrent lease obligation							(207)
Noncurrent deferred tax liability							(355)
Other noncurrent liabilities							(532)
Total liabilities							(1,865)
Net assets acquired							$ 9,749

[1] Goodwill in the Technologies reporting unit is net of $1.8 billion of accumulated impairment losses.

[2] *Prior-period information has been restated for the retrospective application of a change in accounting principle related to the amortization of actuarial gains and losses for our qualified U.S. government pension plans, which we adopted in the fourth quarter of 2020. For further discussion of this change in accounting principle, see Note T to the Consolidated Financial Statements.

[3] Goodwill in the Information Technology and Mission Systems reporting units is net of $536 and $1.3 billion of accumulated impairment losses, respectively.