Annual report pursuant to Section 13 and 15(d)

Business and Summary of Significant Accounting Principles (Wireless Acquisition Narrative) (Details)

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Business and Summary of Significant Accounting Principles (Wireless Acquisition Narrative) (Details) - USD ($)
$ in Millions
 12 Months Ended
Feb. 02, 2015
Dec. 31, 2016
Dec. 31, 2015
Noncontrolling Interest [Line Items]      
Payments to acquire assets and interest $ 293.2    
Other Income (Expense)      
Noncontrolling Interest [Line Items]      
Gain from adjustment to fair value   $ 3.1  
Other Income (Expense) | Rights to Receive Future Capacity      
Noncontrolling Interest [Line Items]      
Gain from adjustment to fair value $ 1.2    
Other Income (Expense) | Rights to Use Capacity      
Noncontrolling Interest [Line Items]      
Impairment of intangible assets     $ 3.8