Deferred Revenue and Performance Obligations (Details) $ in Billions	12 Months Ended
	Dec. 31, 2018 USD ($)
Revenue from Contract with Customer [Abstract]
Deferred revenue recognized	$ 1.1
Remaining non-cancelable performance obligations	$ 4.9
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Performance obligations expected to be satisfied (percent)	50.00%
Remaining performance obligation, expected timing of satisfaction, period	12 months