Revenues and Contract Costs - Schedule of Cost Incurred to Obtain or Fulfill Contracts with Customers (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Capitalized Contract Cost [Line Items]
Cost incurred to obtain or fulfill contracts with customers	$ 4,246,000,000		$ 4,246,000,000		$ 4,489,000,000
Contract with Customer, Asset, Credit Loss Expense (Reversal)	$ 0	$ 0	$ 0	$ 0
Minimum
Capitalized Contract Cost [Line Items]
Deferred contract cost, amortization period	2 years		2 years
Maximum
Capitalized Contract Cost [Line Items]
Deferred contract cost, amortization period	5 years		5 years
Prepaid expenses and other
Capitalized Contract Cost [Line Items]
Cost incurred to obtain or fulfill contracts with customers	$ 2,455,000,000		$ 2,455,000,000		2,578,000,000
Other assets
Capitalized Contract Cost [Line Items]
Cost incurred to obtain or fulfill contracts with customers	$ 1,791,000,000		$ 1,791,000,000		$ 1,911,000,000