Tower Obligations - Narrative (Details) $ in Millions		1 Months Ended	12 Months Ended
	Jan. 01, 2019 tower_site	Dec. 31, 2019 tower_site	Dec. 31, 2015 USD ($) tower_site	Dec. 31, 2012 USD ($) tower_site	Dec. 31, 2018
Sale Leaseback Transaction [Line Items]
Number of wireless communications tower sites sold		168
Minimum
Sale Leaseback Transaction [Line Items]
Lessee leasing arrangements, operating leases, term of contract (years)		5 years			5 years
Maximum
Sale Leaseback Transaction [Line Items]
Lessee leasing arrangements, operating leases, term of contract (years)		10 years			10 years
Tower Transaction
Sale Leaseback Transaction [Line Items]
Number of wireless communications tower sites sold				7,100
Net proceeds, financing activities | $				$ 2,500
Property subject to failed sale leaseback transaction, number of units	6,200
Lessee leasing arrangements, operating leases, term of contract (years)			10 years	10 years
Sale leaseback transaction, fixed-price purchase options | $				$ 2,000
Sale Leaseback, Interest Rate				8.00%
Tower Transaction | Minimum
Sale Leaseback Transaction [Line Items]
Lessee leasing arrangements, operating leases, term of contract (years)				23 years
Tower Transaction | Maximum
Sale Leaseback Transaction [Line Items]
Lessee leasing arrangements, operating leases, term of contract (years)				37 years
Tower Transaction PTI
Sale Leaseback Transaction [Line Items]
Net proceeds, financing activities | $			$ 140
Property subject to failed sale leaseback transaction, number of units			150
Sale Leaseback, Interest Rate			5.00%