Business Combinations - Narrative (Details) - USD ($)				3 Months Ended	12 Months Ended
	Jul. 26, 2019	May 18, 2018	Apr. 29, 2018	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018
DISH | T-Mobile and Sprint | Prepaid Business
Business Acquisition [Line Items]
Payments for asset acquisition	$ 1,400,000,000
DISH | T-Mobile and Sprint | Prepaid Business | Transition Services Agreement
Business Acquisition [Line Items]
Transition period (up to)	3 years
DISH | T-Mobile and Sprint | Prepaid Business | Master Network Services Agreement
Business Acquisition [Line Items]
Transition period (up to)	7 years
DISH | T-Mobile and Sprint | Spectrum Licenses
Business Acquisition [Line Items]
Payments for asset acquisition	$ 3,600,000,000
Additional lease period	2 years
T-Mobile and Sprint | DISH | Decommissioned Towers and Retail Locations
Business Acquisition [Line Items]
Option period (up to)	5 years
Sprint
Business Acquisition [Line Items]
Exchange ratio (in shares)			0.10256
Exchange ratio (in shares)			9.75
Fully-diluted shares of combined company held by public stockholders (percent)					31.30%
Required fees by acquirer upon consummation					$ 0
Required reimbursement by acquiree upon termination, percentage		33.00%
Required reimbursement of consent, bank, and other fees paid or accrued					18,000,000
Accrued required reimbursement by acquiree upon termination					0
Required reimbursement by acquirer upon termination, percentage		67.00%
Required reimbursement by acquirer upon termination					162,000,000
Accrued required reimbursement by acquirer upon termination					0
Costs recognized associated with merger transaction					620,000,000	$ 196,000,000
Payments for Merger-related costs					442,000,000	86,000,000
Required payment resulting from failure to satisfy closing condition of business combination agreement (up to)			$ 600,000,000
Sprint | Deutsche Telekom AG
Business Acquisition [Line Items]
Payments for requisite consents to DT			$ 13,000,000
Payments of consent fees				$ 7,000,000
Sprint | Senior Notes
Business Acquisition [Line Items]
Payments for requisite consents to third-party note holders		$ 95,000,000		$ 54,000,000
Payments of consent fees					$ 242,000,000
Sprint | Deutsche Telekom AG
Business Acquisition [Line Items]
Fully-diluted shares expected to be held immediately following merger (percent)					41.50%
Required fees by acquirer upon consummation					$ 0	$ 0
Sprint | SoftBank
Business Acquisition [Line Items]
Fully-diluted shares expected to be held immediately following merger (percent)					27.20%