Revenue Recognition (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue recognized which was included in the contract liability balance	$ 248
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining revenue performance obligation, optional exemption, contract term	3 years
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Remaining revenue performance obligation, optional exemption, contract term	5 years