Intangible Assets and Goodwill (Guardian Digital Communications Limited Acquisition) (Details) - Guardian Digital Communications Limited (GDCL) $ in Millions			12 Months Ended
	Feb. 19, 2016 USD ($)	Feb. 19, 2016 GBP (£)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Consideration transferred, excluding third party debt paid and liabilities assumed | £		£ 1
Aggregate purchase price	$ 1,000	698,000,000
Deferred cash payment | £		£ 64,000,000
Net sale from operations of Airwave			$ 462
Net earnings from operations of Airwave			$ 57
Consideration transferred	1,100
Net present value of deferred consideration payment to former owners	$ 82
Discount rate used to calculate net present value	4.20%	4.20%
Useful life of intangibles	7 years	7 years
Customer Relationships
Business Acquisition [Line Items]
Acquired intangible assets	$ 846
Trade Names
Business Acquisition [Line Items]
Acquired intangible assets	$ 29