Annual report pursuant to Section 13 and 15(d)

Business and Summary of Significant Accounting Principles (Impact of AWN NCI Acquisition) (Details)

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Business and Summary of Significant Accounting Principles (Impact of AWN NCI Acquisition) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Feb. 02, 2015
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Noncontrolling Interest [Line Items]        
Reduction of non-controlling interest   $ 1,138 $ 14,445 $ 281,803
Increase in deferred tax assets $ 8,445      
Fair value of consideration paid for acquisition of equity interest 303,831      
Non-controlling Interests        
Noncontrolling Interest [Line Items]        
Reduction of non-controlling interest 268,364     271,521
Additional paid-in capital        
Noncontrolling Interest [Line Items]        
Reduction of non-controlling interest $ 27,022 $ 1,138 $ 14,445 $ 10,282