Commitments and Contingencies - Joint-Owned Utility Poles (Details)	12 Months Ended
Dec. 31, 2016 county item
Loss Contingencies [Line Items]
Number of counties \| county	3
Number of utilities	3
Dispute resolution process
Loss Contingencies [Line Items]
Number of utilities	1

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.

Name:	us-gaap_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration