Summary of Significant Accounting Policies (Narrative) (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2019 USD ($) Swap $ / shares	Sep. 29, 2019 $ / shares	Jun. 30, 2019 $ / shares	Mar. 31, 2019 $ / shares	Dec. 31, 2018 USD ($) Swap $ / shares	Sep. 30, 2018 $ / shares	Jul. 01, 2018 $ / shares	Apr. 01, 2018 USD ($) $ / shares	Dec. 31, 2019 USD ($) Swap $ / shares	Dec. 31, 2018 USD ($) Swap $ / shares	Dec. 31, 2017 USD ($) $ / shares	May 31, 2019 USD ($)
Significant Accounting Policies [Line Items]
Performance obligations satisfied in previous periods									$ 709,000,000	$ 636,000,000	$ 520,000,000
Remaining Performance Obligation	$ 48,752,000,000								48,752,000,000
Research and Development Expense									$ 732,000,000	841,000,000	700,000,000
Cash And Cash Equivalent Maturities Date									P90D
Restricted Cash and Cash Equivalents	6,000,000				$ 16,000,000				$ 6,000,000	16,000,000
Proceeds from Sale of Short-term Investments									0	0
Deferred precontract costs, work in process inventories	182,000,000				163,000,000				182,000,000	163,000,000
Deferred Commissions	55,000,000				$ 55,000,000				55,000,000	55,000,000
Amortization of Deferred Commissions									26,000,000	$ 45,000,000	$ 28,000,000
Capitalized Software Development Costs for Software Sold to Customers	$ 0								$ 0
Favorable (unfavorable) impact to EPS, Basic | $ / shares	$ 3.16	$ 3.08	$ 2.92	$ 2.77	$ 2.93	$ 2.25	$ 2.78	$ 2.20	$ 11.94	$ 10.16	$ 6.96
Favorable (unfavorable) impact to EPS, Diluted | $ / shares	$ 3.16	$ 3.08	$ 2.92	$ 2.77	$ 2.93	$ 2.25	$ 2.78	$ 2.19	$ 11.93	$ 10.15	$ 6.95
Amortization of net actuarial loss									$ 1,060,000,000	$ 1,362,000,000	$ 1,187,000,000
Cash Flow Hedge Gain to be Reclassified within Twelve Months	$ 3,000,000								$ 3,000,000
Number of years pension and PRB gain and losses spread									3 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Explanation									We expect to recognize revenue on approximately half and three-quarters of the remaining performance obligations over the next 12 and 24 months, respectively, with the remainder recognized thereafter.
Reclassification of stranded tax effects										0
Minimum [Member]
Significant Accounting Policies [Line Items]
Operating Cycle									P1Y
Maximum [Member]
Significant Accounting Policies [Line Items]
Foreign currency forward contracts, off-set or netting provisions, fair value of counterparty default exposure	1,000,000				$ 1,000,000				$ 1,000,000	$ 1,000,000
Revenue Benchmark [Member] | US Government Contacts Excluding FMS Sales [Member]
Significant Accounting Policies [Line Items]
Sales breakout									69.00%	68.00%	67.00%
Revenue Benchmark [Member] | International Sales, including Foreign Military Sales [Member]
Significant Accounting Policies [Line Items]
Sales breakout									29.00%	30.00%	32.00%
Foreign Exchange Forward [Member]
Significant Accounting Policies [Line Items]
Derivative, Notional Amount	1,487,000,000				1,772,000,000				$ 1,487,000,000	$ 1,772,000,000
Foreign Currency Forward Contracts Net Notional Exposure	$ 746,000,000				$ 840,000,000				746,000,000	$ 840,000,000
Foreign currency forward contracts maturing in next 12 months									922,000,000
Foreign currency forward contracts maturing in next two years									315,000,000
Foreign currency forward contracts maturing in next three years									122,000,000
Foreign currency forward contracts maturing in the next four years and thereafter									$ 128,000,000
Interest Rate Swap [Member]
Significant Accounting Policies [Line Items]
Interest rate swaps outstanding | Swap	0				0				0	0
Treasury Lock [Member]
Significant Accounting Policies [Line Items]
Derivative, Notional Amount	$ 0				$ 0				$ 0	$ 0		$ 375,000,000
Derivative, Loss on Derivative									17,000,000
Fair Value, Inputs, Level 2 [Member]
Significant Accounting Policies [Line Items]
Short-term Investments	0				$ 0				$ 0	0
AOCI Attributable to Parent [Member]
Significant Accounting Policies [Line Items]
Reclassification of stranded tax effects								$ (1,451,000,000)		(1,451,000,000)
Retained Earnings [Member]
Significant Accounting Policies [Line Items]
Reclassification of stranded tax effects								$ 1,451,000,000		$ 1,451,000,000
Redemption Value Adjustment in Excess of Fair Value [Member]
Significant Accounting Policies [Line Items]
Favorable (unfavorable) impact to EPS, Basic | $ / shares									$ 0.00	$ 0.01	$ 0.00
Favorable (unfavorable) impact to EPS, Diluted | $ / shares									$ 0	$ 0.01	$ 0.00
Computer Software [Member]
Significant Accounting Policies [Line Items]
Computer Software, net, estimated useful lives, in years									10 years
ASU 2016-02 [Member] | Assets, Total [Member]
Significant Accounting Policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification										$ 805,000,000
ASU 2016-02 [Member] | Liabilities, Total [Member]
Significant Accounting Policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification										(841,000,000)
ASU 2016-02 [Member] | Other Current Liabilities [Member]
Significant Accounting Policies [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification										(194,000,000)
Pension Plan [Member]
Significant Accounting Policies [Line Items]
Amortization of net actuarial loss									$ 1,050,000,000	$ 1,351,000,000	$ 1,177,000,000
SAUDI ARABIA
Significant Accounting Policies [Line Items]
Remaining Performance Obligation	$ 2,900,000,000								$ 2,900,000,000
SAUDI ARABIA | Maximum [Member]
Significant Accounting Policies [Line Items]
Kingdom of Saudi Arabia net sales, as a percent of total net sales									5.00%