Acquisition of NTELOS Holdings Corp. and Exchange with Sprint - Narrative (Details)			3 Months Ended			8 Months Ended	12 Months Ended
	May 06, 2016 USD ($) installment shares	May 05, 2016 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Borrowing amount			$ 847,875,000			$ 847,875,000	$ 847,875,000	$ 201,250,000
Repayment of borrowing amount							213,793,000	23,000,000	$ 5,750,000
Integration and acquisition expenses							42,232,000	$ 3,546,000	$ 0
Term Loan [Member]
Business Acquisition [Line Items]
Repayment of borrowing amount	$ 195,500,000
Customer Based Contract Rights [Member] | Nonmonentary Exchange of Intangibles [Member] | Sprint [Member]
Business Acquisition [Line Items]
Nonmonetary transaction amount	206,700,000
Additional Customer Based Contract Rights [Member] | Nonmonentary Exchange of Intangibles [Member] | Sprint [Member]
Business Acquisition [Line Items]
Nonmonetary transaction amount	$ 120,900,000
Gain on nonmonetary transfer, period of recognition	6 years
Spectrum Licenses [Member] | Nonmonentary Exchange of Intangibles [Member] | Sprint [Member]
Business Acquisition [Line Items]
Nonmonetary transaction amount	$ 198,200,000
Affiliate Contract Agreement [Member] | Nonmonentary Exchange of Intangibles [Member] | Sprint [Member]
Business Acquisition [Line Items]
Nonmonetary transaction amount	284,100,000
Ntelos Holding, Corp [Member]
Business Acquisition [Line Items]
Consideration	$ 667,800,000
Adjustment to depreciation expense					$ 4,600,000
Extension in term of affiliate relationship agreement with sprint	5 years
Limit of waived fee under affiliate agreement	$ 251,800,000.0
Period for additional waiver of management fee	6 months
Letters of credit		$ 2,200,000
Percentage of amount to cover each disbursement and performance default penalty of total eligible awards		10.00%
Business acquisition, number of shares issued (in shares) | shares	380,000
Number of installment | installment	5
Number of pending installment | installment	4
Remaining period for payment of shares acquired value	4 years
Business acquisition, shares issued value	$ 10,400,000
Integration and acquisition expenses	90,000,000
Debt issuance cost	23,000,000
Severance costs							54,700,000
Ntelos Holding, Corp [Member] | Cost of Sales [Member]
Business Acquisition [Line Items]
Severance costs							1,300,000
Ntelos Holding, Corp [Member] | Selling, General and Administrative Expenses [Member]
Business Acquisition [Line Items]
Severance costs							$ 11,100,000
Ntelos Holding, Corp [Member] | Term Loan [Member]
Business Acquisition [Line Items]
Borrowing amount	$ 810,000,000
Average effective interest rate	3.84%
Repayment of borrowing amount	$ 521,600,000
Ntelos Holding, Corp [Member] | Minimum [Member]
Business Acquisition [Line Items]
Before amendment right or obligation to sell business	80.00%
Ntelos Holding, Corp [Member] | Maximum [Member]
Business Acquisition [Line Items]
After amendment right or obligation to sell business	90.00%
Management fee charge by Sprint	$ 4,200,000.0
Additional waiver of management fee	$ 5,000,000.0
Winning bid eligible to receive, amount		$ 5,000,000.0
Ntelos Holding, Corp [Member] | Customer Based Contract Rights [Member]
Business Acquisition [Line Items]
Intangibles, revision, increase (decrease)				$ (24,500,000)		$ 8,546,000
Amortization expense, revision, increase (decrease)				(500,000)
Ntelos Holding, Corp [Member] | Additional Customer Based Contract Rights [Member]
Business Acquisition [Line Items]
Intangibles, revision, increase (decrease)			7,100,000
Amortization expense, revision, increase (decrease)				400,000	$ 300,000
Ntelos Holding, Corp [Member] | Additional Customer Based Contract Rights [Member] | Minimum [Member]
Business Acquisition [Line Items]
Affiliate contract agreement	4 years
Ntelos Holding, Corp [Member] | Additional Customer Based Contract Rights [Member] | Maximum [Member]
Business Acquisition [Line Items]
Affiliate contract agreement	10 years
Ntelos Holding, Corp [Member] | Affiliate Contract Agreement [Member]
Business Acquisition [Line Items]
Intangibles, revision, increase (decrease)			3,700,000	$ 29,700,000
Affiliate contract agreement	14 years			14 years
Amortization expense, revision, increase (decrease)			$ 100,000	$ 400,000