Revenue Recognition - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Performance obligation, amount	$ 191
Business Customer
Disaggregation of Revenue [Line Items]
Customer life	49 months
Minimum
Disaggregation of Revenue [Line Items]
Contract term	1 year
Minimum | Business Customer
Disaggregation of Revenue [Line Items]
Customer life	49 months
Maximum
Disaggregation of Revenue [Line Items]
Contract term	7 years
Average | Consumer Customers
Disaggregation of Revenue [Line Items]
Customer life	30 months