Acquisition of NTELOS Holdings Corp. and Exchange with Sprint - Narrative (Details)			3 Months Ended		5 Months Ended	9 Months Ended
	May 06, 2016 USD ($) installment shares	May 05, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Borrowing amount			$ 828,937,000		$ 828,937,000	$ 828,937,000		$ 201,250,000
Repayment of borrowing amount						207,816,000	$ 17,250,000
Integration and acquisition expenses			15,272,000	$ 2,129,000		35,801,000	$ 3,153,000
Term Loan [Member]
Business Acquisition [Line Items]
Repayment of borrowing amount	$ 195,500,000
Spectrum Licenses [Member] | Sprint [Member] | Nonmonentary Exchange of Intangibles [Member]
Business Acquisition [Line Items]
Nonmonentary transaction amount	198,200,000
Customer Based Contract Rights [Member] | Sprint [Member] | Nonmonentary Exchange of Intangibles [Member]
Business Acquisition [Line Items]
Nonmonentary transaction amount	203,400,000
Additional Customer Based Contract Rights [Member] | Sprint [Member] | Nonmonentary Exchange of Intangibles [Member]
Business Acquisition [Line Items]
Nonmonentary transaction amount	$ 113,800,000
Gain on nonmonentary transfer, period of recognition	6 years
Affiliate Contract Agreement [Member] | Sprint [Member] | Nonmonentary Exchange of Intangibles [Member]
Business Acquisition [Line Items]
Nonmonentary transaction amount	$ 287,800,000
NTELOS Holdings Corp. [Member]
Business Acquisition [Line Items]
Consideration	$ 665,400,000
Property, plant and equipment, revisions, original appraised value					4,600,000
Property, plant and equipment, revisions, appraisal adjustment					1,000,000
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
Debt issuance cost	24,000,000
Severance costs			20,200,000			43,900,000
NTELOS Holdings Corp. [Member] | Cost of Goods and Services [Member]
Business Acquisition [Line Items]
Severance costs			700,000			1,000,000
NTELOS Holdings Corp. [Member] | Selling, General and Administrative Costs [Member]
Business Acquisition [Line Items]
Severance costs			4,200,000			$ 7,100,000
NTELOS Holdings Corp. [Member] | Term Loan [Member]
Business Acquisition [Line Items]
Borrowing amount	$ 810,000,000
Average effective interest rate	3.84%
Repayment of borrowing amount	$ 519,700,000
NTELOS Holdings Corp. [Member] | Minimum [Member]
Business Acquisition [Line Items]
Before amendment right or obligation to sell business	80.00%
Integration and acquisition expenses	$ 106,000,000.0
NTELOS Holdings 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
Integration and acquisition expenses	$ 126,000,000
NTELOS Holdings Corp. [Member] | Customer Based Contract Rights [Member]
Business Acquisition [Line Items]
Intangibles, revision, increase (decrease)			(24,500,000)		$ 5,162,000
Amortization expense, revision, increase (decrease)			(500,000)
NTELOS Holdings Corp. [Member] | Additional Customer Based Contract Rights [Member] | Minimum [Member]
Business Acquisition [Line Items]
Useful Life	4 years
NTELOS Holdings Corp. [Member] | Additional Customer Based Contract Rights [Member] | Maximum [Member]
Business Acquisition [Line Items]
Useful Life	10 years
NTELOS Holdings Corp. [Member] | Affiliate Contract Agreement [Member]
Business Acquisition [Line Items]
Intangibles, revision, increase (decrease)			$ 29,700,000
Useful Life	14 years		14 years
Amortization expense, revision, increase (decrease)			$ 400,000