Summary of Significant Accounting Policies (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	May 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Discontinued operations, net of tax	$ 0	$ 13,000,000	$ 0
Trading securities	0	0
Other contract costs	144,000,000	135,000,000
Operating lease liability	1,503,000,000
ROU assets	1,432,000,000
Notes
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issued					$ 7,500,000,000
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease liability				$ 1,400,000,000
ROU assets				$ 1,400,000,000
Company-sponsored R & D, including product development costs
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Research and development expense	466,000,000	$ 502,000,000	$ 521,000,000
Discontinued Operations, Disposed of by Sale
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Discontinued operations, net of tax	13,000,000
Information Technology
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Impairment of reporting unit	$ 0
Fair value of reporting unit in excess of carrying amount	25.00%