Acquisitions (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	$ 377	$ 195
Goodwill arising from acquisitions	310
Goodwill, Purchase Accounting Adjustments	(106)
Hydroid, Inc. [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired	377
Cash acquired	2
Goodwill arising from acquisitions	310
Goodwill, Purchase Accounting Adjustments	(71)
Intangible Assets	$ 76
Fulcrum IT Services, LLC
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired			$ 195
Cash acquired			1
Goodwill arising from acquisitions			133
Goodwill, Purchase Accounting Adjustments			(1)
Intangible Assets			$ 49