Business and Summary of Significant Accounting Principles (Wireless Equipment Installment Plan (EIP) Receivables) (Details)	12 Months Ended
Dec. 31, 2017 payment
Loans and Leases Receivable Disclosure [Line Items]
Number of installment plan payments	12
Maximum
Loans and Leases Receivable Disclosure [Line Items]
Installment period to purchase wireless devices	24 months

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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