Segment Information - Additional Information (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($) regional_operating_unit customer	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) segment category regional_operating_unit customer	Jun. 30, 2018 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | segment			5
Number of global enterprise customers | customer	200		200
Number of operating regions | regional_operating_unit	3		3
Universal service taxes and surcharges | $	$ 232	$ 229	$ 480	$ 476
International and Global Accounts
Segment Reporting Information [Line Items]
Number of categories of products and services			4
Consumer
Segment Reporting Information [Line Items]
Number of categories of products and services			4