The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Section 45
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Basis of presentation and significant accounting policies.

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BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Jan. 15, 2016
Basis Of Presentation And Significant Accounting Policies [Line Items]
Net income	$ 23.4	$ 27.0	$ 58.1	$ 62.5
Basic and diluted earnings per share	$ 0.09	$ 0.11	$ 0.23	$ 0.26
Allstream
Basis Of Presentation And Significant Accounting Policies [Line Items]
Percentage of entity acquired					100.00%
Change in accounting estimate
Basis Of Presentation And Significant Accounting Policies [Line Items]
Depreciation expense	$ 17.4
Net income	$ 11.7
Basic and diluted earnings per share	$ 0.05
Fiber optic network \| Change in accounting estimate
Basis Of Presentation And Significant Accounting Policies [Line Items]
Estimated useful life in years	33 years
Owned buildings
Basis Of Presentation And Significant Accounting Policies [Line Items]
Estimated useful life in years	39 years
Owned buildings \| Change in accounting estimate
Basis Of Presentation And Significant Accounting Policies [Line Items]
Estimated useful life in years	45 years
Minimum \| Fiber optic network
Basis Of Presentation And Significant Accounting Policies [Line Items]
Estimated useful life in years	15 years
Maximum \| Fiber optic network
Basis Of Presentation And Significant Accounting Policies [Line Items]
Estimated useful life in years	20 years