Zayo 10-Q 8 Feb 18 2018 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Dec. 31, 2017	Feb. 02, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Entity Registrant Name	Zayo Group Holdings, Inc.
Entity Central Index Key	1,608,249
Current Fiscal Year End Date	--06-30
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		248,064,095

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2017	Jun. 30, 2017
Current assets
Cash and cash equivalents	$ 280.8	$ 220.7
Trade receivables, net of allowance of $8.7 and $9.5 as of December 31, 2017 and June 30, 2017, respectively	233.8	191.6
Prepaid expenses	67.4	68.3
Other assets	24.4	34
Total current assets	606.4	514.6
Property and equipment, net	5,129.4	5,016
Intangible assets, net	1,302.8	1,188.6
Goodwill	1,712.9	1,840.2
Deferred income taxes, net	38	38.3
Other assets	146.4	141.7
Total assets	8,935.9	8,739.4
Current liabilities
Accounts payable	42.7	72.4
Accrued liabilities	330.5	325.4
Accrued interest	73	63.5
Current portion of long-term debt	5	5
Capital lease obligations, current	8.4	8
Deferred revenue, current	152	146
Total current liabilities	611.6	620.3
Long-term debt, non-current	5,538.6	5,532.7
Capital lease obligation, non-current	89.8	93.6
Deferred revenue, non-current	989.9	989.7
Deferred income taxes, net	147.7	40.2
Other long-term liabilities	48	52.4
Total liabilities	7,425.6	7,328.9
Stockholders' equity
Common stock, $0.001 par value - 850,000,000 shares authorized; 248,105,766 and 246,471,551 shares issued and outstanding as of December 31, 2017 and June 30, 2017, respectively	0.2	0.2
Additional paid-in capital	1,931.2	1,884
Accumulated other comprehensive income	23.3	5.4
Accumulated deficit	(444.4)	(479.1)
Total stockholders' equity	1,510.3	1,410.5
Total liabilities and stockholders' equity	$ 8,935.9	$ 8,739.4

CONDENSED CONSOLIDATED BALANCE3

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Jun. 30, 2017
CONDENSED CONSOLIDATED BALANCE SHEETS
Trade receivables allowance	$ 8.7	$ 9.5
Preferred Stock, par value	$ 0.001	$ 0.001
Preferred Stock, shares authorized	50,000,000	50,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	850,000,000	850,000,000
Common stock, shares issued	248,105,766	246,471,551
Common stock, shares outstanding	248,105,766	246,471,551

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Revenue	$ 653.5	$ 506.7	$ 1,297	$ 1,011.6
Operating costs and expenses
Operating costs (excluding depreciation and amortization and including stock-based compensation—Note 8)	232	179.9	467.7	353.7
Selling, general and administrative expenses (including stock-based compensation—Note 8)	121.6	104.7	249.9	210.3
Depreciation and amortization	195.9	131.4	380	269.9
Total operating costs and expenses	549.5	416	1,097.6	833.9
Operating income	104	90.7	199.4	177.7
Other expenses
Interest expense	(73.1)	(53.7)	(146.7)	(107)
Loss on extinguishment of debt			(4.9)
Foreign currency gain/(loss) on intercompany loans	3.1	(17.4)	13.9	(28.6)
Other income/(expense), net	0.4	0.4	1.3	0.2
Total other expenses, net	(69.6)	(70.7)	(136.4)	(135.4)
Income from operations before income taxes	34.4	20	63	42.3
Provision for income taxes	22.9	0.2	28.3	6.8
Net income	$ 11.5	$ 19.8	$ 34.7	$ 35.5
Weighted-average shares used to compute net income per share:
Basic	247.4	243.1	246.9	242.9
Diluted	249.3	245.6	249.2	244.9
Net income per share:
Basic	$ 0.05	$ 0.08	$ 0.14	$ 0.15
Diluted	$ 0.05	$ 0.08	$ 0.14	$ 0.14

CONDENSED CONSOLIDATED STATEME5

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME/(LOSS)
Net income	$ 11.5	$ 19.8	$ 34.7	$ 35.5
Foreign currency translation adjustment, net of tax	0.8	(24.1)	22.9	(26.2)
Defined benefit pension plan adjustments, net of tax	(5)		(5)	(1.2)
Comprehensive income/(loss)	$ 7.3	$ (4.3)	$ 52.6	$ 8.1

CONDENSED CONSOLIDATED STATEME6

CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS’ EQUITY - 6 months ended Dec. 31, 2017 - USD ($) $ in Millions	Common Stock	Additional paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Total
Balance at Jun. 30, 2017	$ 0.2	$ 1,884	$ 5.4	$ (479.1)	$ 1,410.5
Balance, shares at Jun. 30, 2017	246,471,551				246,471,551
Stock-based compensation		47.2			$ 47.2
Stock-based compensation, shares	1,634,215
Foreign currency translation adjustment, net of tax			22.9		22.9
Defined benefit pension plan adjustments, net of tax			(5)		(5)
Net income				34.7	34.7
Balance at Dec. 31, 2017	$ 0.2	$ 1,931.2	$ 23.3	$ (444.4)	$ 1,510.3
Balance, shares at Dec. 31, 2017	248,105,766				248,105,766

CONDENSED CONSOLIDATED STATEME7

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities
Net income	$ 34.7	$ 35.5
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	380	269.9
Loss on extinguishment of debt	4.9
Non-cash interest expense	4.8	5.1
Stock-based compensation	51.3	66.5
Amortization of deferred revenue	(66.4)	(55.6)
Foreign currency (gain)/loss on intercompany loans	(13.9)	28.6
Deferred income taxes	19.7	(0.5)
Provision for bad debts	2.3	1.4
Non-cash loss on investments	0.3	0.5
Changes in operating assets and liabilities, net of acquisitions
Trade receivables	(41.5)	(16.5)
Accounts payable and accrued liabilities	29.2	(33)
Additions to deferred revenue	61.9	84.3
Other assets and liabilities	(10.8)	16.3
Net cash provided by operating activities	456.5	402.5
Cash flows from investing activities
Purchases of property and equipment	(386.8)	(421.9)
Cash paid for acquisitions, net of cash acquired		(1.3)
Other	(0.2)	1.5
Net cash used in investing activities	(387)	(421.7)
Cash flows from financing activities
Proceeds from debt	312.8
Principal payments on long-term debt	(313.2)
Principal payments on capital lease obligations	(4)	(2)
Payment of debt issuance costs	(3.4)	(0.7)
Cash paid for Santa Clara acquisition financing arrangement	(2.6)
Net cash used in financing activities	(10.4)	(2.7)
Net cash flows	59.1	(21.9)
Effect of changes in foreign exchange rates on cash	1	(4.8)
Net increase/(decrease) in cash and cash equivalents	60.1	(26.7)
Cash and cash equivalents, beginning of year	220.7	170.7
Cash and cash equivalents, end of period	280.8	144
Supplemental disclosure of non-cash investing and financing activities:
Cash paid for interest, net of capitalized interest	136.3	97.3
Cash paid for income taxes	3.1	6
Non-cash purchases of equipment through capital leasing	0.3	37.9
(Decrease)/increase in accounts payable and accrued expenses for purchases of property and equipment	$ (47.4)	$ 22.7

BUSINESS AND BASIS OF PRESENTAT

BUSINESS AND BASIS OF PRESENTATION	6 Months Ended
	Dec. 31, 2017
BUSINESS AND BASIS OF PRESENTATION
BUSINESS AND BASIS OF PRESENTATION	(1) BUSINESS Business Zayo Group Holdings, Inc., a Delaware corporation, was formed on November 13, 2007, and is the parent company of a number of subsidiaries engaged in providing access to bandwidth infrastructure. Zayo Group Holdings, Inc. and its subsidiaries are collectively referred to as “Zayo Group Holdings” or the “Company.” The Company’s primary operating subsidiary is Zayo Group, LLC (“ZGL”). Headquartered in Boulder, Colorado, the Company supplies high-bandwidth infrastructure, including fiber networks and data centers, and provides access to bandwidth infrastructure to users in the United States (“U.S.”), Canada and Europe. The Company provides its products and offerings through six segments: · Fiber Solutions, including dark fiber and mobile infrastructure solutions. · Transport, including wavelength, wholesale IP and SONET solutions. · Enterprise Networks, including Ethernet, private lines, dedicated Internet and cloud-based computing and storage products. · Colocation, including provision of colocation space and power and interconnection offerings. · Voice, unified communications and offerings dedicated to small and medium sized businesses. · Other offerings, including Zayo Professional Services (“ZPS”). The Company’s shares are listed on the New York Stock Exchange (NYSE) under the ticker symbol “ZAYO”. Basis of Presentation The accompanying condensed consolidated financial statements include all the accounts of the Company and its wholly-owned subsidiaries. All inter-company accounts and transactions have been eliminated in consolidation. The accompanying condensed consolidated financial statements and related notes are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial reporting and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for quarterly reports on Form 10-Q, and do not include all of the note disclosures required by GAAP for complete financial statements. These condensed consolidated financial statements should, therefore, be read in conjunction with the consolidated financial statements and notes thereto for the year ended June 30, 2017 included in the Company’s Annual Report on Form 10-K for the year ended June 30, 2017. In the opinion of management, all adjustments considered necessary for a fair presentation of financial position, results of operations and cash flows of the Company have been included herein. The results of operations for the three and six months ended December 31, 2017 are not necessarily indicative of the operating results for any future interim period or the full year. The Company’s fiscal year ends June 30 each year, and we refer to the fiscal year ending June 30, 2019 as “Fiscal 2019”, the fiscal year ending June 30, 2018 as “Fiscal 2018” and the fiscal year ended June 30, 2017 as “Fiscal 2017.” Earnings per Share Basic earnings per share attributable to the Company’s common shareholders is computed by dividing net earnings attributable to common shareholders by the weighted average number of common shares outstanding for the period. Diluted earnings per share attributable to common shareholders presents the dilutive effect, if any, on a per share basis of potential common shares (such as restricted stock units) as if they had been vested or converted during the periods presented. The Company’s computation of diluted income per share for the three and six months ended December 31, 2017 included an adjustment of 1. 9 million and 2. 3 million shares, respectively, and for the three and six months ended December 31, 2016 included an adjustment of 2.5 million and 2.0 million shares, respectively, to the weighted-average shares to account for the dilutive effect of the Part A and Part B restricted stock units (“RSUs”) and related issuance of common shares upon vesting (see Note 8 – Stock-based Compensation ) (calculated using the treasury method). Significant Accounting Policies the Company acquired defined benefit pension plans and other non-pension post-retirement benefits (“OPEBs”) that cover qualifying foreign employees. The pension plans and OPEBs were legally transferred to the Company during the three months ended December 31, 2017. Eligibility and the level of benefits for these plans varies depending on participants’ status, date of hire and or length of service. The Company recognizes the funded status of these defined benefit and post-retirement plans as an asset or a liability on the condensed consolidated balance sheet. Each year's actuarial gains or losses and prior period service costs are a component of other comprehensive income/(loss), which is then included in accumulated other comprehensive income. Pension and post-retirement benefit expenses are recognized over the period in which the employee renders service and becomes eligible to receive benefits. The pension and post-retirement accruals and valuations are dependent on actuarial assumptions to calculate those amounts. These assumptions include discount rates, long-term rate of return on plan assets, retirement rates, mortality rates and other factors. A change in any of the above assumptions would have an effect on the projected benefit obligation and pension expense. See Note 9 – Employee Benefits , for additional disclosure regarding the Company’s defined benefit pension plans and OPEBs. The Company’s policy is to fund the pension plans in accordance with applicable regulations. The OPEBs are not funded. There have been no other changes to the Company’s significant accounting policies described in its Annual Report on Form 10-K for the year ended June 30, 2017. Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reporting period. Significant estimates are used when establishing allowances for doubtful accounts and accruals for billing disputes, determining useful lives for depreciation and amortization and accruals for exit activities associated with real estate leases, assessing the need for impairment charges (including those related to intangible assets and goodwill), determining the fair values of assets acquired and liabilities assumed in business combinations, accounting for income taxes and related valuation allowances against deferred tax assets, determining the defined benefit costs and defined benefit obligations related to post-employment benefits, determining the fair value of plan assets related to post-employment benefits and estimating certain restricted stock unit grant fair values used to compute the stock-based compensation liability and expense. Management evaluates these estimates and judgments on an ongoing basis and makes estimates based on historical experience, current conditions, and various other assumptions that are believed to be reasonable under the circumstances. The results of these estimates form the basis for making judgments about the carrying values of assets and liabilities as well as identifying and assessing the accounting treatment with respect to commitments and contingencies. Actual results may differ from these estimates under different assumptions or conditions. Recently Issued Accounting Pronouncements In March 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2017-07, Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . This ASU requires an employer to report the service cost component of net periodic pension cost and net periodic postretirement cost in the same line item in the statement of operations as other compensation costs arising from services rendered by the related employees during the period. The other net cost components are required to be presented in the statement of operations separately from the service cost component and outside a subtotal of income from operations. Additionally, the line item used in the statement of operations to present the other net cost components must be disclosed in the notes to the financial statements. This ASU is effective for fiscal years beginning after December 15, 2017 (Fiscal 2019 for the Company), and interim periods within those fiscal years, and must be applied on a retrospective basis. Had the Company adopted this ASU in the quarter it would not have resulted in a material impact to the financial statements for the three and six months ended December 31, 2017. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classifications of Certain Cash Receipts and Cash Payments. The new standard provides guidance for eight changes with respect to how cash receipts and cash payments are classified in the statement of cash flows, with the objective of reducing diversity in practice. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 31, 2017 (Fiscal 2019 for the Company), with early adoption permitted. The Company does not plan to early adopt, nor does it expect the adoption of this new standard to have a material impact on its condensed consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases . The new guidance supersedes existing guidance on accounting for leases in Topic 840 and is intended to increase the transparency and comparability of accounting for lease transactions. ASU 2016-02 requires most leases to be recognized on the balance sheet. Lessees will need to recognize a right-of-use asset and a lease liability for virtually all leases. The liability will be equal to the present value of lease payments. The asset will be based on the liability, subject to adjustment, such as for initial direct costs. For income statement purposes, the FASB retained a dual model, requiring leases to be classified as either operating or finance. Lessor accounting remains similar to the current model, but updated to align with certain changes to the lessee model and the new revenue recognition standard (ASU 2014-09). The ASU will require both quantitative and qualitative disclosures regarding key information about leasing arrangements. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018 (Fiscal 2020 for the Company) . Early adoption is permitted. The standard must be adopted using a modified retrospective transition, and provides for certain practical expedients. Transition will require application of the new guidance at the beginning of the earliest comparative period presented. The Company established a project team and commenced an initial impact assessment process. To date, the Company has reviewed a sample of lessee and lessor arrangements and made preliminary assessments of the impact this standard will have on the consolidated financial statements. Although it is still assessing the impact of this standard, the Company expects the new guidance to significantly increase the reported assets and liabilities on the consolidated balance sheets. There are currently no plans to early adopt this ASU. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers , which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance under GAAP when it becomes effective. In July 2015, the FASB deferred the effective date to annual reporting periods and interim reporting periods within annual reporting periods beginning after December 15, 2017 (Fiscal 2019 for the Company) . Early adoption was permitted as of the original effective date or annual reporting periods and interim reporting periods within annual reporting periods beginning after December 15, 2016. The standard permits the use of either the retrospective or cumulative effect transition method . In Fiscal 2017, the Company established a project team and commenced an initial assessment to determine the impact ASU 2014-09 will have on the Company’s revenue arrangements. Lease revenue is not included in the scope of ASU 2014-09, and as a result, the revenue to which the Company must apply the new guidance is generally limited to solutions revenue, certain maintenance revenue not covered by lease arrangements, certain transactions that include the title transfer of integral components to customers and other fees charged to customers. Although the Company is still assessing the impact of this standard on its consolidated financial statements, it has preliminarily determined that due to changes in the timing of recognition of certain installations, discounts and promotional credits given to customers, there may be additional contract assets and liabilities recorded in the consolidated balance sheets upon adoption. Additionally, the requirement to defer incremental costs incurred to acquire a contract including sales commissions, and recognize such costs over the contract period or expected customer life may result in additional deferred charges recognized in the consolidated balance sheets and could have the impact of deferring operating expenses. The assessment of the impact of this standard on the Company’s consolidated financial statements also includes developing new accounting policies, internal controls and procedures and possible changes to our systems to facilitate the adoption of this accounting policy. The Company will adopt this new standard as of July 1, 2018 and, based on its current assessment, expects to apply the modified retrospective method, which may result in a cumulative effect adjustment as of the date of adoption. The Company's initial assessment of changes to the reporting of its revenue and expenses and anticipated adoption method may change depending on the results of the Company’s ongoing and final assessment of this ASU. Until the Company is further along in its assessment, it does not anticipate being able to provide reasonably accurate estimates of the impact of ASU 2014-09.

ACQUISITIONS

ACQUISITIONS	6 Months Ended
	Dec. 31, 2017
ACQUISITIONS
ACQUISITIONS	(2) ACQUISITIONS Since inception through December 31, 2017, the Company has consummated 4 1 transactions accounted for as business combinations. The acquisitions were executed as part of the Company’s business strategy of expanding through acquisitions. The acquisitions of these businesses have allowed the Company to increase the scale at which it operates, which in turn affords the Company the ability to increase its operating leverage, extend its network reach, and broaden its customer base. The accompanying condensed consolidated financial statements include the operations of the acquired entities from their respective acquisition dates. Acquisitions Announced During Fiscal 2018 Spread Networks On November 26, 2017, the Company entered into a definitive agreement to acquire Spread Networks, LLC, a privately-owned telecommunications provider that owns and operates a 825-mile, high-fiber count long haul route connecting New York and Chicago, for $127.0 million in cash (subject to post-closing adjustments). The all-cash transaction is expected to be funded with cash on hand and debt and is expected to close in the first calendar quarter of 2018, subject to customary closing conditions. The route will connect 755 Secaucus Road in Secaucus, New Jersey and 1400 Federal Boulevard in Carteret, New Jersey to 350 Cermak Road in Chicago, Illinois, with additional connectivity to be enabled by Zayo’s existing network. Zayo plans to use the acquired assets to provide a low-latency wavelength route from Seattle to New York. Optic Zoo Networks and Neutral Path Communications See Note 14- Subsequent Events . Acquisitions Completed During Fiscal 2017 KIO Networks US Data Centers On May 1, 2017, the Company completed the $11.9 million cash acquisition of Castle Access, Inc.’s (d/b/a “KIO Networks US”) San Diego, California data centers. The two data centers, located at 12270 World Trade Drive and 9606 Aero Drive, total more than 100,000 square feet of space and two megawatts (MW) of critical IT power, with additional power available. As of December 31, 2017, $1.2 million of the purchase consideration is being held in escrow pending the expiration of the indemnification adjustment period. The acquisition was funded with cash on hand and was considered a stock purchase for tax purposes. Electric Lightwave Parent, Inc. On March 1, 2017, the Company acquired Electric Lightwave Parent, Inc. (“Electric Lightwave”) , an infrastructure and telecommunications solutions provider serving 35 markets in the western U.S., for net purchase consideration of $1,426. 6 million, net of cash acquired, subject to certain post-closing adjustments . As of December 31, 2017, $7.0 million of the purchase consideration is being held in escrow pending the expiration of the indemnification adjustment period. The acquisition was funded through debt (see Note 5 – Long-Term Debt) and cash on hand. The acquisition was considered a stock purchase for tax purposes. The acquisition added 8,100 route miles of long haul fiber and 4,000 miles of dense metro fiber across Denver, Minneapolis, Phoenix, Portland, Seattle, Sacramento, San Francisco, San Jose, Salt Lake City, Spokane and Boise, with on-net connectivity to more than 3,100 enterprise buildings and 100 data centers. Santa Clara Data Center Acquisition On October 3, 2016, the Company acquired a data center in Santa Clara, California (the “Santa Clara Data Center”) for net purchase consideration of $11.3 million. The net purchase consideration represents the net present value of ten quarterly payments of approximately $1.3 million beginning in the December 2016 quarter. As of December 31, 2017, the remaining cash consideration to be paid was $6.4 million. The acquisition was considered an asset purchase for tax purposes and a business combination for accounting purposes. Payments made to the previous owners of the Santa Clara Data Center during the six months ended December 31, 2017 of $2.5 million, representing the principal portion of the financing arrangement, are included in the accompanying condensed consolidated statement of cash flows within financing activities. The Santa Clara Data Center, located at 5101 Lafayette Street, includes 26,900 total square feet and three MW of critical IT power. The facility also includes high-efficiency power and cooling infrastructure, seismic reinforcement and proximity to Zayo’s long haul dark fiber routes between San Francisco and Los Angeles. Acquisition Method Accounting Estimates The Company initially recognizes the assets and liabilities acquired from the aforementioned acquisitions based on its preliminary estimates of their acquisition date fair values. As additional information becomes known concerning the acquired assets and assumed liabilities, management may make adjustments to the opening balance sheet of the acquired company up to the end of the measurement period, which is no longer than a one year period following the acquisition date. The determination of the fair values of the acquired assets and liabilities assumed (and the related determination of estimated lives of depreciable tangible and identifiable intangible assets) requires significant judgment. During the three months ended December 31, 2017, the Company recorded revised fair value estimates of its customer relationship intangible asset and property and equipment associated with the Electric Lightwave acquisition resulting in increases to intangible assets and property and equipment of $160.2 million and $52.2 million, respectively, with corresponding decreases to goodwill. Accordingly, the tax basis of assets was also updated during the three months ended December 31, 2017 resulting in a decrease to deferred tax assets of $80.2 million, or a $35.2 million deferred tax liability position. for the KIO Networks US Data Centers and Electric Lightwave acquisitions, the Company has not completed its fair value analysis and calculations in sufficient detail necessary to arrive at the final estimates of the fair value of certain working capital and non-working capital acquired assets and assumed liabilities, including the allocations to goodwill and intangible assets, property and equipment and resulting deferred taxes. All information presented with respect to certain working capital and non-working capital acquired assets and liabilities assumed as it relates to these acquisitions is preliminary and subject to revision pending the final fair value analysis. The table below reflects the Company's estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2017 acquisitions: KIO Networks US Data Centers Electric Lightwave Santa Clara Data Acquisition date May 1, 2017 March 1, 2017 October 3, 2016 (in millions) Cash $ 0.1 $ 12.6 $ — Other current assets 0.1 55.0 — Property and equipment 2.4 572.8 31.9 Deferred tax assets, net 1.8 — — Intangibles 6.4 472.4 6.0 Goodwill 2.9 498.4 — Other assets 0.5 1.7 — Total assets acquired 14.2 1,612.9 37.9 Current liabilities 1.7 57.4 — Deferred tax liabilities, net — 35.1 — Capital lease obligations — — 26.6 Deferred revenue 0.5 80.0 — Other liabilities — 1.2 — Total liabilities assumed 2.2 173.7 26.6 Net assets acquired 12.0 1,439.2 11.3 Less cash acquired (0.1) (12.6) — Total consideration paid/payable $ 11.9 $ 1,426.6 $ 11.3 The goodwill arising from the Company’s acquisitions results from synergies, anticipated incremental sales to the acquired company customer base and economies-of-scale expected from the acquisitions. The Company has allocated the goodwill to the reporting units (in existence on the respective acquisition dates) that were expected to benefit from the acquired goodwill. The allocation was determined based on the excess of the estimated fair value of the reporting unit over the estimated fair value of the individual assets acquired and liabilities assumed that were assigned to the reporting units. See Note 3 – Goodwill for the allocation of the Company's acquired goodwill to each of its reporting units. In the Company’s acquisitions, the Company acquired certain customer relationships. These relationships represent a valuable intangible asset, as the Company anticipates continued business from the acquired customer bases. The Company’s estimate of the fair value of the acquired customer relationships is generally based on a multi-period excess earnings valuation technique that utilizes Level 3 inputs. Transaction Costs Transaction costs include expenses associated with professional services (i.e., legal, accounting, regulatory, etc.) rendered in connection with signed and/or closed acquisitions or disposals, travel expense, severance expense incurred associated with acquisitions or disposals, and other direct expenses incurred that are associated with signed and/or closed acquisitions or disposals and unsuccessful acquisitions. The Company incurred transaction costs of $5.9 million and $14.2 million for the three and six months ended December 31, 2017, respectively, and $6.2 million and $9.2 million for the three and six months ended December 31, 2016, respectively. Transaction costs have been included in selling, general and administrative expenses in the condensed consolidated statements of operations and in cash flows from operating activities in the condensed consolidated statements of cash flows during these periods.

GOODWILL

GOODWILL	6 Months Ended
	Dec. 31, 2017
GOODWILL
GOODWILL	(3) GOODWILL The Company’s goodwill balance was $1,712.9 million and $1,840.2 million as of December 31, 2017 and June 30, 2017, respectively. The Company’s reporting units are comprised of its strategic product groups (“SPG” or “SPGs”). Effective January 1, 2017, the Company implemented organizational changes that had an impact on the composition of the Company’s SPGs . The change in structure had the impact of consolidating and/or regrouping existing SPGs, disaggregating the legacy Zayo Canada SPG among the existing SPGs and creating a new Allstream and IP Transit SPG (See Note 13 – Segment Reporting ). In connection with the organizational change, goodwill was re-allocated to the Company’s SPGs on a relative fair value basis. The Company completed an assessment immediately prior to and after the organizational change at the SPG level and determined that it is more likely than not that the fair value of the Company’s reporting units is greater than their carrying amounts. As of December 31, 2017, the Company’s SPGs were comprised of the following: Fiber Solutions, Zayo Wavelength Solutions (“Waves”), Zayo IP Transit Solutions (“IP Transit”), Zayo SONET Solutions (“SONET”), Zayo Ethernet Solutions (“Ethernet”), Enterprise Private and Connectivity (“EPIC”), Zayo Cloud Solutions (“Cloud”), Zayo Colocation (“zColo"), Allstream and Other (primarily Zayo Professional Services). The following reflects the changes in the carrying amount of goodwill during the six months ended December 31, 2017: Product Group As of June 30, 2017 Adjustments to Fiscal 2017 Foreign Currency As of December 31, 2017 (in millions) Fiber Solutions $ 633.9 $ 145.5 $ 3.1 $ 782.5 Waves 247.4 (62.3) 1.6 186.7 Sonet 52.0 30.9 0.1 83.0 Ethernet 359.5 (263.6) 0.2 96.1 EPIC 89.5 80.0 0.3 169.8 zColo 256.3 2.7 1.3 260.3 Cloud 69.5 (4.9) 0.1 64.7 Allstream 116.5 (62.3) — 54.2 Other 15.6 — 15.6 Total $ 1,840.2 $ (134.0) $ 6.7 $ 1,712.9

INTANGIBLE ASSETS

INTANGIBLE ASSETS	6 Months Ended
	Dec. 31, 2017
INTANGIBLE ASSETS
INTANGIBLE ASSETS	(4) INTANGIBLE ASSETS Identifiable intangible assets as of December 31, 2017 and June 30, 2017 were as follows: Gross Carrying Amount Accumulated Net (in millions) December 31, 2017 Finite-Lived Intangible Assets Customer relationships $ 1,643.9 $ (361.1) $ 1,282.8 Underlying rights 1.6 (0.5) 1.1 Total 1,645.5 (361.6) 1,283.9 Indefinite-Lived Intangible Assets Certifications 3.5 — 3.5 Underlying Rights 15.4 — 15.4 Total $ 1,664.4 $ (361.6) $ 1,302.8 June 30, 2017 Finite-Lived Intangible Assets Customer relationships $ 1,477.7 $ (308.6) $ 1,169.1 Underlying rights 1.6 (0.4) 1.2 Total 1,479.3 (309.0) 1,170.3 Indefinite-Lived Intangible Assets Certifications 3.5 — 3.5 Underlying Rights 14.8 — 14.8 Total $ 1,497.6 $ (309.0) $ 1,188.6

LONG-TERM DEBT

LONG-TERM DEBT	6 Months Ended
	Dec. 31, 2017
LONG-TERM DEBT
LONG-TERM DEBT	(5) LONG-TERM DEBT As of December 31, 2017 and June 30, 2017, long-term debt was as follows: Date of Outstanding as of Issuance or most Maturity Interest Interest Rate December 31, June 30, (in millions) Term Loan Facility due 2021 Jan 2017 Jan 2021 Monthly LIBOR +2.00% $ 496.3 $ 498.8 B-2 Term Loan Facility Jul 2017 Jan 2024 Monthly LIBOR +2.25% 1,119.3 1,429.9 6.00% Senior Unsecured Notes Jan & Mar 2015 Apr 2023 Apr/Oct 6.00% 1,430.0 1,430.0 6.375% Senior Unsecured Notes May 2015 & Apr 2016 May 2025 May/Nov 6.375% 900.0 900.0 5.75% Senior Unsecured Notes Jan, Apr & Jul 2017 Jan 2027 Jan/Ju1 5.75% 1,650.0 1,350.0 Total obligations 5,595.6 5,608.7 Unamortized premium/(discounts), net 11.4 (3.2) Unamortized debt issuance costs (63.4) (67.8) Carrying value of debt 5,543.6 5,537.7 Less current portion (5.0) (5.0) Total long-term debt, less current portion $ 5,538.6 $ 5,532.7 Term Loan Facility and Revolving Credit Facility On May 6, 2015, ZGL and Zayo Capital, Inc. (“Zayo Capital”) entered into an Amendment and Restatement Agreement whereby the Credit Agreement (the “Credit Agreement”) governing their senior secured term loan facility (the “Term Loan Facility”) and $450.0 million senior secured revolving credit facility (the “Revolver”) was amended and restated in its entirety. The amended and restated Credit Agreement extended the maturity date of a portion of the outstanding term loans under the Term Loan Facility from July 2, 2019 to May 6, 2021. The terms of the Term Loan Facility require the Company to make quarterly principal payments of 25 basis points per quarter of the original loan amount (unless reduced by any prepayments) plus an annual payment of up to 50% of excess cash flow, as determined in accordance with the Credit Agreement (no such annual payment was required during Fiscal 2017 or Fiscal 2016). On January 15, 2016, ZGL and Zayo Capital entered into an Incremental Amendment (the “Amendment”) to the Credit Agreement. Under the terms of the Amendment, the portion of the Term Loan Facility due 2021 was increased by $400.0 million (the “Incremental Term Loan”). The additional amounts borrowed bear interest at LIBOR plus 3.5% with a minimum LIBOR rate of 1.0%. The $400.0 million add-on was priced at 99.0%. No other terms of the Credit Agreement were amended. The Incremental Term Loan proceeds were used to fund the Allstream Acquisition and for general corporate purposes. On July 22, 2016, ZGL and Zayo Capital entered into a Repricing Amendment (the “Repricing Amendment”) to the Credit Agreement. Per the terms of the Repricing Amendment, the Incremental Term Loan was repriced at par and will bear interest at a rate of LIBOR plus 2.75%, with a minimum LIBOR rate of 1.0%, which represented a downward adjustment of 75 basis points. No other terms of the Credit Agreement were amended. On January 19, 2017, ZGL and Zayo Capital entered into an Incremental Amendment No. 2 (the “Incremental Amendment”) to the Company’s Credit Agreement. Per the terms of the Incremental Amendment, the existing $1.85 billion of term loans under the Credit Agreement were repriced at 99.75% with one $500.0 million tranche that bears interest at a rate of LIBOR plus 2.0%, with a minimum LIBOR rate of 0.0% and a maturity date of four years from incurrence, which represents a downward adjustment of 75 basis points along with the lowering of the previous LIBOR floor, and a second $1.35 billion tranche (the “B-2 Term Loan” and along with the $500.0 million tranche, the “Refinancing Term Loans”) that bears interest at a rate of LIBOR plus 2.5%, with a minimum LIBOR rate of 1.0% and a maturity of seven years from incurrence, which represents a downward adjustment of 25 basis points. In addition, per the terms of the Incremental Amendment, ZGL and Zayo Capital added a new $650.0 million term loan tranche under the Credit Agreement (the “Electric Lightwave Incremental Term Loan”) that bears interest at LIBOR plus 2.5%, with a minimum LIBOR rate of 1.0%, with a maturity of seven years from the closing date of the Incremental Amendment. In connection with the Incremental Amendment the full $2,500.0 million Term Loan Facility, including the Refinancing Term Loans and the Electric Lightwave Incremental Term Loan, was re-issued at a price of 99.75%. No other material terms of the Credit Agreement with respect to the Refinancing Term Loans and the Electric Lightwave Incremental Term Loan were amended. On April 10, 2017, $570.1 million of the B-2 Term Loan and the Electric Lightwave Incremental Term Loan was repaid from proceeds of issuance of senior unsecured notes as further discussed below. Additionally, in July 2017, $310.7 million of the B-2 Term Loan was repaid from the proceeds of issuance of senior unsecured notes as further discussed below. On July 20, 2017, ZGL and Zayo Capital entered into a second repricing (the “Repricing Amendment No. 2”) to the Credit Agreement. Per the terms of the Repricing Amendment No. 2, the outstanding balances of the B-2 Term Loan and Electric Lightwave Incremental Term Loan were repriced at par and will bear interest at a rate of LIBOR plus 2.25%, with a minimum LIBOR rate of 1.0%, which represented a downward adjustment of 25 basis points. No other terms of the Credit Agreement were amended. In connection with the Repricing Amendment No. 2, the Company recognized an expense of $4.9 million during the three months ended September 30, 2017 associated with debt extinguishment. The $4.9 million loss on extinguishment of debt primarily represents non-cash expenses associated with the write-off of unamortized debt issuance costs and the issuance discounts on the portion of the Credit Agreement, as further amended. The loss on extinguishment of debt also includes certain fees paid to third parties involved in the Repricing Amendment No. 2. On December 22, 2017, ZGL and Zayo Capital entered into a third repricing (the “Repricing Amendment No. 3”) to the Credit Agreement. Per the terms of the Repricing Amendment No. 3, the Revolver under the Credit Agreement was repriced and will bear interest at a rate of LIBOR plus 1.00% to LIBOR plus 1.75% per annum based on the Company’s leverage ratio, which represented a downward adjustment of 100 basis points. No other terms of the Credit Agreement were amended. T he Revolver matures on April 17, 2020. The Credit Agreement also allows for letter of credit commitments of up to $50.0 million. The Revolver is subject to a fee per annum of 0.25% to 0.375% (based on ZGL’s current leverage ratio) of the weighted-average unused capacity, and the undrawn amount of outstanding letters of credit backed by the Revolver are subject to a 0.25% fee per annum. Outstanding letters of credit backed by the Revolver are subject to a fee of 1.00% to 1.75% per annum based upon ZGL’s leverage ratio. The weighted average interest rates (including margin) on the Term Loan Facility were approximately 3.7% and 3.4% as of December 31, 2017 and June 30, 2017, respectively. Interest rates on the Revolver as of December 31, 2017 and June 30, 2017 were approximately 3.3% and 3.8%, respectively. As of December 31, 2017, no amounts were outstanding under the Revolver and $1,615.6 million in aggregate principal amount was outstanding under the Term Loan Facility. Standby letters of credit were outstanding in the amount of $8.0 million as of December 31, 2017, leaving $442.0 available under the Revolver. Senior Unsecured Notes 6.00% Senior Unsecured Notes due 2023 On January 23, 2015 and March 9, 2015, ZGL and Zayo Capital completed private offerings of aggregate principal amounts of $700.0 million and $730.0 million, respectively, of 6.00% senior unsecured notes due in 2023 (the “2023 Unsecured Notes”). 6.375% Senior Unsecured Notes due 2025 On April 14, 2016, ZGL and Zayo Capital completed a private offering of $550.0 million aggregate principal amount of 2025 Unsecured Notes (the “Incremental 2025 Notes”). The Incremental 2025 Notes were priced at 97.76% and were an additional issuance of the $350.0 million 6.375% senior unsecured notes due in 2025 that were originally issued on May 6, 2015 (the “2025 Notes” and together with the Incremental 2025 Notes, the “2025 Unsecured Notes”). The net proceeds from the Incremental 2025 Notes, plus cash on hand, were used to (i) redeem the then outstanding $325.6 million 10.125% senior unsecured notes due 2020, including the required $20.3 million make-whole premium and accrued interest, and (ii) repay $196.0 million of borrowings under the then outstanding secured Term Loan Facility. 5.75% Senior Unsecured Notes due 2027 On January 27, 2017, ZGL and Zayo Capital completed a private offering of $800.0 million aggregate principal amount of 5.75% senior unsecured notes due 2027 (the “January 2027 Notes”), which were issued at par. T he net proceeds from the offering, along with the Electric Lightwave Incremental Term Loan discussed above, were used to fund the Electric Lightwave acquisition (see Note 2 – Acquisitions ), which closed on March 1, 2017. On April 10, 2017, the Company completed a private offering of $550.0 million aggregate principal amount of 5.75% senior unsecured notes due 2027 (the “Incremental 2027 Notes”). The Incremental 2027 Notes were an additional issuance of the January 2027 Notes and were priced at 104.0%. The net proceeds from the Incremental 2027 Notes were used to repay certain outstanding balances on the Company’s B-2 Term Loan. On July 5, 2017, the Company completed a private offering of $300.0 million aggregate principal amount of 5.75% senior notes due 2027 (the “July Incremental 2027 Notes” and together with the Incremental 2027 Notes and the January 2027 Notes, the “2027 Unsecured Notes”). The July Incremental 2027 Notes were an additional issuance of the January 2027 Notes and Incremental 2027 Notes and were priced at 104.25%. The net proceeds of $310.7 million from the offering were used to further repay certain outstanding balances on the Company’s B-2 Term Loan. Debt covenants The indentures (the “Indentures”) governing the 2023 Unsecured Notes, the 2025 Unsecured Notes and the 2027 Unsecured Notes (collectively the “Notes”) contain covenants that, among other things, restrict the ability of ZGL and its subsidiaries to incur additional indebtedness and issue preferred stock, pay dividends or make other distributions with respect to any equity interests, make certain investments or other restricted payments, create liens, sell assets, incur restrictions on the ability of ZGL’s restricted subsidiaries to pay dividends or make other payments to ZGL, consolidate or merge with or into other companies or transfer all or substantially all of their assets, engage in transactions with affiliates, and enter into sale and leaseback transactions. The terms of the Indentures include customary events of default. The Credit Agreement contains customary events of default, including among others, non-payment of principal, interest, or other amounts when due, inaccuracy of representations and warranties, breach of covenants, cross default to certain other indebtedness, insolvency or inability to pay debts, bankruptcy, or a change of control. The Credit Agreement also contains a covenant, applicable only to the Revolver, that ZGL maintain a senior secured leverage ratio below 5.25:1.00 at any time when the aggregate principal amount of loans outstanding under the Revolver is greater than 35% of the commitments under the Revolver. The Credit Agreement also requires ZGL and its subsidiaries to comply with customary affirmative and negative covenants, including covenants restricting the ability of ZGL and its subsidiaries, subject to specified exceptions, to incur additional indebtedness, make additional guaranties, incur additional liens on assets, or dispose of assets, pay dividends, or make other distributions, voluntarily prepay certain other indebtedness, enter into transactions with affiliated persons, make investments and amend the terms of certain other indebtedness. The Indentures limit any increase in ZGL’s secured indebtedness (other than certain forms of secured indebtedness expressly permitted under the Indentures) to a pro forma secured debt ratio of 4.50 times ZGL’s previous quarter’s annualized modified EBITDA (as defined in the Indentures), and limit ZGL’s incurrence of additional indebtedness to a total indebtedness ratio of 6.00 times the previous quarter’s annualized modified EBITDA. The Company was in compliance with all covenants associated with its debt agreements as of December 31, 2017. Guarantees The Notes are fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by all of ZGL’s current and future domestic restricted subsidiaries. The Notes were co-issued with Zayo Capital, which does not have independent assets or operations. The Term Loan Facility and Revolver are fully and unconditionally guaranteed, jointly and severally, on a senior secured basis by all of ZGL’s current and future domestic restricted subsidiaries. Debt issuance costs In connection with the Credit Agreement (and subsequent amendments thereto), and the various Notes offerings, the Company incurred debt issuance costs of $113.1 million (net of extinguishments). These costs are being amortized to interest expense over the respective terms of the underlying debt instruments using the effective interest method, unless extinguished earlier, at which time the related unamortized costs are to be immediately expensed. The balance of debt issuance costs as of December 31, 2017 and June 30, 2017 was $63.4 million and $ 67.8 million, net of accumulated amortization of $ 49.7 million and $ 45.1 million, respectively. The amortization of debt issuance costs is included on the condensed consolidated statements of cash flows within the caption “Non-cash interest expense” along with the amortization or accretion of the premium and discount on the Company’s indebtedness. Interest expense associated with the amortization of debt issuance costs was $2.3 million and $4.7 million for the three and six months ended December 31, 2017, respectively, and $2.2 million and $4.4 million for the three and six months ended December 31, 2016, respectively. Debt issuance costs are presented in the condensed consolidated balance sheets as a reduction to “Long-term debt, non-current.”

INCOME TAXES

INCOME TAXES	6 Months Ended
	Dec. 31, 2017
INCOME TAXES
INCOME TAXES	(6) INCOME TAXES A reconciliation of the actual income tax provision and the tax computed by applying the U.S. federal rate to the earnings before income taxes during the three and six month periods ended December 31, 2017 and 2016 is as follows: Three months ended December 31, Six months ended December 31, 2017 2016 2017 2016 (in millions) Expected provision at the statutory rate $ 7.6 $ 7.1 $ 17.6 $ 14.8 Increase/(decrease) due to: State income tax expense, net of federal benefit 0.9 0.8 1.5 1.5 Stock-based compensation 1.0 (2.9) 2.5 0.4 Transactions costs not deductible for tax purposes 0.1 0.2 0.2 0.3 Change in statutory tax rate, non-U.S. 0.8 — 0.8 (1.7) Foreign tax rate differential 0.5 0.4 (1.7) (0.3) Change in valuation allowance (25.7) (4.4) (31.4) (6.7) U.S. Tax Reform 44.1 — 44.1 — Other, net (6.4) (1.0) (5.3) (1.5) Provision for income taxes $ 22.9 $ 0.2 $ 28.3 $ 6.8 On December 22, 2017, the U.S. federal government enacted a tax bill, H.R.1, An Act to Provide for Reconciliation Pursuant to Titles II and V of the Concurrent Resolution on the Budget for Fiscal Year 2018 , previously known as Tax Cuts and Jobs Act of 2017 (“U.S. Tax Reform”). U.S. Tax Reform reduced the U.S. corporate tax rate from 35% to 21%, created a territorial tax system with a one-time mandatory repatriation tax on previously deferred foreign earnings, and changed business-related deductions and credits. Many of the U.S. Tax Reform provisions are effective January 01, 2018; however, ASC 740, Income Taxes , requires companies to recognize the effect of tax law changes in the period of enactment. The SEC staff issued SAB 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (“SAB 118”), which will allow registrants to record provisional amounts during a ‘measurement period’. The measurement period is similar to the measurement period used when accounting for business combinations under ASC 805, Business Combinations . SAB 118 allows a registrant to recognize provisional amounts when it does not have the necessary information available, prepared or analyzed (including computations) in reasonable detail to complete its accounting for the change in tax law. The measurement period ends when a registrant has obtained, prepared and analyzed the information necessary to finalize its accounting, but cannot extend beyond one year. In accordance with SAB 118, the Company has recorded provisional amounts because actual year-end amounts for the following items are not yet known: income, capital expenditures, foreign exchange rates, foreign distributable reserves, foreign earnings and profits, and foreign cash balances. Management is in the process of obtaining and evaluating further information related to the provisional amounts estimated for items including the mandatory repatriation amounts and impacts to deferred tax assets and liabilities. Management has made estimates as it anticipates additional guidance and legislative action from the U.S. Federal and State governments in addition to interpretations and guidance from the SEC and FASB regarding the application of U.S. Tax Reform. Future adjustments to the provisional numbers will be recorded as discrete adjustments to income tax expense in the period in which those adjustments become estimable and/or are finalized. Some U.S. Tax Reform provisions are effective for years beginning after December 31, 2017, which would be the Company’s Fiscal 2019, including the tax on global intangible low taxed income (“GILTI”), Base Erosion and Anti-abuse Tax” (“BEAT”), interest expense limitations, and executive compensation limitations. We continue to evaluate these and other impacts of U.S. Tax Reform as more information and guidance becomes available. Provisional amounts recognized due to the U.S. Tax Reform for the three and six months ended December 31, 2017: Tax Expense Deferred Tax Liability Current Tax Receivable (in millions) Change in statutory tax rate, U.S. only (AMT credit is now refundable) $ 1.4 $ 11.4 $ 10.0 Changes to indefinite reinvestment assertion 7.9 7.9 Repatriation Tax (offset against net operating loss carryforwards, non-cash) 34.8 34.8 Net discrete impacts of the enactment of U.S. Tax Reform $ 44.1 $ 54.1 $ 10.0 The interim period effective tax rate is driven from year-to-date and anticipated pre-tax book income for the full fiscal year adjusted for anticipated items that are deductible/non-deductible for tax purposes only (i.e., permanent items). Additionally, the tax expense or benefit related to discrete permanent differences in an interim period are recorded in the period in which they occur. The determination of the effective tax rate is based upon a number of significant estimates and judgments; therefore, there can be significant volatility in interim tax provisions. The following statutory tax rates were used to determine the tax provision. Fiscal 2017 Fiscal 2018 Fiscal 2019 Tax Rates Federal Rate 35% 28% 21% Blended Federal & State Rate 39% 33% 26% The interim effective tax rate for the three and six months ended December 31, 2017 was positively impacted by reversing the valuation allowance of $28.5 million on the deferred tax assets of certain Canadian subsidiaries. In addition, the “Other, net” category includes a benefit of $6.9 million for the provision to return adjustment for entities in France. The effective tax rate was negatively impacted by U.S. Tax Reform principally relating to the estimated income tax on the deemed repatriation of previously deferred foreign earnings. The Company files income tax returns in various federal, state, and local jurisdictions including the United States, Canada, United Kingdom and France. In the normal course of business, the Company is subject to examination by taxing authorities throughout the world. With few exceptions, the Company is no longer subject to income tax examinations by tax authorities in major tax jurisdictions for years before 2012. As of December 31, 2017, the Company had a $0.2 million current liability for uncertain tax positions related to state taxing jurisdictions, including $0.1 million of accrued interest and penalties. We recognize interest and penalties related to uncertain tax positions in income tax expense. The entire balance is expected to be settled within the next year. Recognition of the uncertain tax positions would impact the effective tax rate because the uncertain tax positions are permanent differences instead of timing differences. As of December 31, 2017, the Company had reversed its indefinite reinvestment assertion on all its foreign subsidiaries because the Company will be required to pay tax on all the accumulated undistributed earnings of its foreign subsidiaries. In accordance with SAB 118, the Company recorded a provisional amount of $7.9 million as a discrete deferred tax liability for additional estimated tax due upon actual repatriation.

EQUITY

EQUITY	6 Months Ended
	Dec. 31, 2017
EQUITY
EQUITY	(7) EQUITY During the six months ended December 31, 2017, the Company recorded a $47.2 million increase in additional paid-in capital associated with stock-based compensation expense related to the Company’s equity classified stock-based compensation awards (See Note 8 – Stock-based Compensation ).

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	6 Months Ended
	Dec. 31, 2017
STOCK-BASED COMPENSATION
STOCK-BASED COMPENSATION	(8) STOCK-BASED COMPENSATION The following tables summarize the Company’s stock-based compensation expense for liability and equity classified awards included in the condensed consolidated statements of operations. Three months ended December 31, Six months ended December 31, 2017 2016 2017 2016 (in millions) Included in: Operating costs $ 2.3 $ 3.3 $ 5.5 $ 6.6 Selling, general and administrative expenses 21.2 31.2 45.8 59.9 Total stock-based compensation expense $ 23.5 $ 34.5 $ 51.3 $ 66.5 CII common units $ — $ 5.9 $ — $ 10.1 Part A restricted stock units 19.4 18.8 41.6 40.1 Part B restricted stock units 3.6 9.5 8.7 15.7 Part C restricted stock units 0.5 0.3 1.0 0.6 Total stock-based compensation expense $ 23.5 $ 34.5 $ 51.3 $ 66.5 CII Common Units During the three and six months ended December 31, 2016, the Company recognized $5.9 million and $10.1 million, respectively, of stock-based compensation expense related to vesting of common units of Communications Infrastructure Investments, LLC (“CII”). On December 31, 2016, the CII common units became fully vested and as such there is no compensation cost associated with CII common units for the three and six months ended December 31, 2017. Performance Compensation Incentive Program During October 2014, the Company adopted the 2014 Performance Compensation Incentive Program (“PCIP”). The PCIP includes incentive cash compensation and equity (in the form of RSUs). Grants under the PCIP RSU plans are made quarterly for all participants. The PCIP was effective on October 16, 2014 and will remain in effect for a period of 10 years (or through October 16, 2024) unless it is earlier terminated by the Company’s Board of Directors. The PCIP has the following components: Part A Under Part A of the PCIP, certain full-time employees, including the Company’s executives, are eligible to earn quarterly awards of RSUs. Each participant in Part A of the PCIP will have an RSU annual award target value, which will be allocated to each fiscal quarter. The final Part A value awarded to a participant for any fiscal quarter is determined by the Compensation Committee of the Board of Directors subsequent to the end of the respective performance period taking into account the Company’s measured value creation for the quarter, as well as such other subjective factors that it deems relevant (including group and individual level performance factors). The number of Part A RSUs granted will be calculated based on the final award value determined by the Compensation Committee divided by the average closing price of the Company’s common stock over the last ten trading days of the respective performance period. Part A RSUs will vest assuming continuous employment fifteen months subsequent to the end of the performance period (for awards relating to periods through June 30, 2017) or twelve months subsequent to the end of the performance period (for awards relating to the period ended September 30, 2017, and subsequent quarters). Upon vesting, the RSUs convert to an equal number of shares of the Company’s common stock. Additionally, under Part A of the PCIP, awards may be granted to certain employees upon commencement of their employment with the Company. During the three and six months ended December 31, 2017, the Company recognized $19.4 million and $41.6 million, respectively, of compensation expense associated with the vested portion of the Part A awards. During the three and six months ended December 31, 2016, the Company recognized $18.8 million and $40.1 million, respectively, of compensation expense associated with the vested portion of the Part A awards. The December 2017 and June 2017 quarterly awards were recorded as liabilities totaling $6.0 million and $5.5 million, as of December 31, 2017 and June 30, 2017, respectively, as the awards represent an obligation denominated in a fixed dollar amount to be settled in a variable number of shares during the subsequent quarter. The quarterly stock-based compensation liability is included in “Accrued liabilities” in the accompanying condensed consolidated balance sheets. Upon the issuance of the RSUs, the liability is re-measured and then reclassified to additional paid-in capital, with a corresponding charge (or credit) to stock based compensation expense. The value of the remaining unvested RSUs is expensed ratably through the vesting date. At December 31, 2017, the remaining unrecognized compensation cost to be expensed over the remaining vesting period for Part A awards is $27.3 million. The following table summarizes the Company’s Part A RSU activity for the six months ended December 31, 2017: Number of Part A Weighted average Weighted average Outstanding at July 1, 2017 2,364,386 $ 31.63 7.1 Granted 1,158,872 34.96 Vested (1,460,389) 31.54 Forfeited (193,105) n/a Outstanding at December 31, 2017 1,869,764 $ 33.42 7.4 Part B Under Part B of the PCIP, participants, including the Company’s executives, are awarded quarterly grants of RSUs. The number of the RSUs earned by the participants is based on the Company’s stock price performance over a performance period of one year with the starting price being the average closing price over the last ten trading days of the quarter immediately prior to the grant and vest. The RSUs vest assuming continuous employment through the end of the measurement period, twelve months after the beginning of the performance period (for awards vesting on or prior to June 30, 2018) or fifteen months after the beginning of the performance period (for awards vesting after June 30, 2018). The existence of a vesting provision that is associated with the performance of the Company’s stock price is a market condition, which affects the determination of the grant date fair value. Upon vesting, RSUs earned convert to an equal number of shares of the Company’s common stock. The following table summarizes the Company’s Part B RSU activity for the six months ended December 31, 2017: Number of Part B Weighted average Weighted average Outstanding at July 1, 2017 411,973 $ 42.86 6.1 Granted 246,516 27.28 Vested (252,529) 52.49 Forfeited (6,636) n/a Outstanding at December 31, 2017 399,324 $ 27.30 6.0 The table below reflects the total Part B RSUs granted during Fiscal 2018 and 2017, the maximum eligible shares of the Company’s common stock that the respective Part B RSU grant could be converted into shares of the Company’s common stock, and the grant date fair value per Part B RSU during the period indicated. The table below also reflects the units converted to the Company’s common stock at a vesting date that is subsequent to the period indicated for those RSUs granted during the period indicated: During the three months ended December 31, September 30, Part B RSUs granted 82,556 163,960 Maximum eligible shares of the Company's common stock 569,636 590,256 Grant date fair value per Part B RSU $ $ Units converted to Company's common stock at vesting date n/a n/a During the three months ended June 30, 2017 March 31, 2017 December 31, 2016 September 30, 2016 Part B RSUs granted 152,808 171,316 191,015 200,425 Maximum eligible shares of the Company's common stock 550,109 880,564 981,817 1,030,185 Grant date fair value per Part B RSU $ 26.52 $ 27.39 $ 75.56 $ 47.00 Units converted to Company's common stock at vesting date n/a 41,368 102,511 99,508 During the three and six months ended December 31, 2017, the Company recognized stock-based compensation expense of $3.6 million and $8.7 million, respectively, related to Part B awards. During the three and six months ended December 31, 2016, the Company recognized stock-based compensation expense of $9.5 million and $15.7 million, respectively, related to Part B awards. The grant date fair value of Part B RSU grants is estimated utilizing a Monte Carlo simulation. This simulation estimates the ten-day average closing stock price ending on the vesting date, the stock price performance over the performance period, and the number of common shares to be issued at the vesting date. Various assumptions are utilized in the valuation method, including the target stock price performance ranges and respective share payout percentages, the Company’s historical stock price performance and volatility, peer companies’ historical volatility and an appropriate risk-free rate. The aggregate future value of the grant under each simulation is calculated using the estimated per share value of the common stock at the end of the vesting period multiplied by the number of common shares projected to be granted at the vesting date. The present value of the aggregate grant is then calculated under each of the simulations, resulting in a distribution of potential present values. The fair value of the grant is then calculated based on the average of the potential present values. The remaining unrecognized compensation cost associated with Part B RSU grants is $5.7 million at December 31, 2017. Part C Under Part C of the PCIP, independent directors of the Company are eligible to receive quarterly awards of RSUs. Independent directors electing to receive a portion of their annual director fees in the form of RSUs are granted a set dollar amount of Part C RSUs each quarter. The quantity of Part C RSUs granted is based on the average closing price of the Company’s common stock over the last ten trading days of the quarter ended immediately prior to the grant date and vest at the end of each quarter for which the grant was made. During the three and six months ended December 31, 2017, the Company’s independent directors were granted 14,261 and 29,947 Part C RSUs, respectively. During the three and six months ended December 31, 2016, the Company’s independent directors were granted 11 ,230 and 2 1,841 Part C RSUs, respectively. During the three and six months ended December 31, 2017, the Company recognized $0.5 million and $1.0 million, respectively, of stock-based compensation expense associated with the Part C awards. During the three and six months ended December 31, 2016, the Company recognized $0.3 million and $0.6 million, respectively, of compensation expense associated with the Part C RSUs.

EMPLOYEE BENEFITS

EMPLOYEE BENEFITS	6 Months Ended
	Dec. 31, 2017
EMPLOYEE BENEFITS
EMPLOYEE BENEFITS	(9) EMPLOYEE BENEFITS In connection with the Allstream Acquisition on January 15, 2016 from Manitoba Telecom Services Inc. (now known as “Bell MTS” as a result of its acquisition by BCE Inc.), Bell MTS agreed to retain the Allstream Acquisition Entity’s former defined benefit pension obligations, and related pension plan assets, of retirees and other former employees of the Allstream Acquisition Entity and also agreed to reimburse the Allstream Acquisition Entity for certain solvency funding payments related to the pension obligations of active employees of the Allstream Acquisition Entity as of January 15, 2016. On October 31, 2017, Bell MTS transferred assets of CAD $117.9 million (or $91.6 million) from the Allstream Acquisition Entity’s former defined benefit pension plans related to pre-closing service obligations for active employees to new defined benefit pension plans of the Allstream Acquisition Entity created by the Company. The plans were transferred on a fully funded basis calculated on a solvency basis, however on a GAAP basis, the plans are underfunded. Upon transfer, a prior period service cost was recognized in other comprehensive income for the underfunded amount, consistent with the Company’s accounting policies. The Company became responsible for accruing post-acquisition liabilities related to these plans as of the Allstream Acquisition Entity date of January 15, 2016. The Company also sponsors an OPEB for former employees of the Allstream Acquisition Entity, which provides health care and life insurance benefits for certain eligible retirees. The Company uses a June 30 annual measurement date for its defined benefit and postretirement benefit plans. Upon the transfer of the pre-closing service obligation, a measurement was obtained. No comparative period figures were disclosed in the tables or notes below, as the amounts for employee benefits were not material for those periods. Defined benefit plans The Company maintains defined benefit pension plans that provide pension benefits for certain former employees of the Allstream Acquisition Entity. Benefits are based on the employee’s length of service and average rate of pay during the highest paid consecutive three years of service. The Company is responsible for adequately funding the pension plans. Contributions are made based on various actuarial cost methods permitted by pension regulatory bodies. Contributions reflect actuarial assumptions about future investment returns, salary projections, future service and life expectancy. Post-retirement benefit plan The Company provides an OPEB plan to certain former employees of the Allstream Acquisition Entity, including, healthcare and life insurance benefits during retirement and other benefits. These OPEB plans are not funded. Benefits are paid directly to the participants of these plans. The following tables provide a reconciliation of the changes in the benefit obligations, fair value of plan assets and the unfunded status for the Company’s defined benefit pension and OPEB, where applicable: Pension Plans (in millions) Change in projected benefit obligation for defined benefit pension plans: Projected benefit obligation at July 1, 2017 $ 6.7 Service cost 1.5 Interest cost 0.7 Actuarial loss (gain) (1.3) Participant contributions 0.3 Benefits paid from plan assets (3.6) Acquisition transfer 102.1 Foreign currency exchange rate changes 0.2 Projected benefit obligation at December 31, 2017 $ 106.6 Post-Retirement Benefit Plans (in millions) Change in projected benefit obligation for OPEB plans Projected benefit obligation at July 1, 2017 $ 9.9 Service cost 0.1 Interest cost 0.2 Benefits paid by Company (0.3) Foreign currency exchange rate changes 0.2 Projected benefit obligation at December 31, 2017 $ 10.1 The accumulated benefit obligation of the defined benefit plan and OPEB at December 31, 2017 are $99.2 million and $10.1 million, respectively. Pension Plans (in millions) Change in pension plan assets Fair value of plan assets at July 1, 2017 $ 3.7 Return on plan assets 1.2 Employer contributions 1.6 Participant contributions 0.3 Benefits paid from plan assets (3.6) Acquisition transfer 93.9 Foreign currency exchange rate changes 0.1 Fair value of pension plan assets at December 31, 2017 $ 97.2 Pension Plans As of December 31, 2017 (in millions) Projected benefit obligation $ 106.6 Fair value of plan assets 97.2 Unfunded status 9.4 Current portion of unfunded status $ — Non-current portion of unfunded status $ 9.4 The following table provides information regarding change in amounts from June 30, 2017 in accumulated other comprehensive loss (“AOCI”) that have not yet been recognized as components of net periodic benefit cost at December 31, 2017: As of June 30, 2017 Deferrals Net Change in AOCI As of December 31, 2017 (in millions) Accumulated other comprehensive loss: Pension plans: Net actuarial (loss)/gain $ — $ 1.3 $ 1.3 $ 1.3 Prior service benefit/(cost) — (8.0) (8.0) (8.0) Deferred income tax benefit/(expense) — 1.7 1.7 1.7 Total pension plans — (5.0) (5.0) (5.0) Post-retirement benefit plans: Net actuarial (loss)/gain (1.2) — — (1.2) Prior service (cost)/benefit — — — — Deferred income tax benefit/(expense) 0.4 — — 0.4 Total post-retirement benefit plans (0.8) — — (0.8) Total accumulated other comprehensive loss $ (0.8) $ (5.0) $ (5.0) $ (5.8) There have been no material amounts reclassified from AOCI during the period. The expected benefit payments for the Company’s defined benefit pension and OPEB plans for the years indicated are as follows: Post-Retirement Pension Plans Benefit Plans (in millions) Year ended June 30, 2018 $ 2.8 $ 0.6 2019 3.0 0.6 2020 3.2 0.6 2021 3.5 0.5 2022 3.7 0.5 2023-2027 22.6 2.5 Net periodic (benefit) cost of the defined benefit pension and OPEB is included in selling, general and administrative expenses in the accompanying condensed consolidated statements of operations includes the following components: Pension Plans Three months ended December 31, 2017 Six months ended December 31, 2017 ( in millions) Service cost $ 0.7 $ 1.5 Interest cost 0.6 0.7 Expected return on plan assets (1.0) (1.1) Net periodic pension benefit income $ 0.3 $ 1.1 OPEB Plans Three months ended December 31, 2017 Six months ended December 31, 2017 (in millions) Service cost $ — $ 0.1 Interest cost 0.1 0.2 Net periodic post-retirement benefit income $ 0.1 $ 0.3 The following tables present the assumptions used in determining benefit obligations of the defined benefit pension and OPEB plans: Pension Plans OPEB Plans Actuarial assumptions: Discount rate Price inflation N/A Expected long-term rate of return on plan assets N/A Rate of compensation increase 2% plus merit & promotion N/A The discount rates utilized reflect the average yield on high quality corporate bonds of similar duration to the plans’ liabilities. The discount rate used to calculate the employee future benefits obligation is determined at each year end by referring to the most recently available market interest rates based on “AA”-rated corporate bond yields reflecting the duration of the employee future benefit plans. Under the yield curve approach, expected future benefit payments for each plan are discounted by a rate on a third-party bond yield curve corresponding to each duration. The yield curve is based on “AA” long-term corporate bonds. A single discount rate is calculated that would yield the same present value as the sum of the discounted cash flows. The expected return on assets assumption for the plans is determined as the estimate of future experience for trust asset returns, reflecting the plans’ current asset allocation and any expected changes during the current plan year, current market conditions and expectations for future market conditions. The investment objective of the defined benefit pension plans is to provide a risk-adjusted return that will ensure the payment of benefits while protecting against the risk of substantial investment losses. Correlations among the asset classes are used to identify an asset mix that the Company believes will provide the most attractive returns. Long-term return forecasts for each asset class using historical data and other qualitative considerations to adjust for projected economic forecasts are used to set the expected rate of return for the entire portfolio. The defined benefit pension plan utilizes various investment securities. Generally, investment securities are exposed to various risks, such as interest rate risks, credit risk, and overall market volatility. Due to the level of risk associated with certain investment securities, it is reasonably possible that changes in the values of investment securities will occur and that such changes could materially affect the amounts reported. The following table presents the Company’s target for the allocation of invested defined benefit pension plan assets at December 31, 2017: As of December 31, 2017 Fixed income Equities Other Total The plans assets are invested in various fund categories utilizing multiple strategies and investment managers. Interests in funds are valued using the net asset value ("NAV") per unit of each fund. The NAV reported by the fund manager is based on the market value of the underlying investments owned by each fund, minus its liabilities, divided by the number of shares outstanding. These funds can be redeemed at NAV, generally at any time. As the funds do not publish publicly available prices, the NAV practical expedient is the most appropriate fair value classification for the plan asset investments. The value associated with these investments is disclosed in the reconciliation of the total investments measured at fair value shown below. The table below presents the fair value of plan assets valued at NAV by category for the pension and post-retirement plans at December 31, 2017. As of December 31, 2017 (in millions) Fixed income $ 36.3 Equities 55.9 Other 5.0 Total $ 97.2 Fixed incom e – Fixed income represents investments in commingled bond funds comprised of Canadian government, corporate bonds, and mortgage-backed securities. Equities – Equities represent investments in commingled equities funds comprised of investments in U.S., Canadian and global equities. Other – Other investments are comprised of investments in commingled real estate funds.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Dec. 31, 2017
FAIR VALUE MEASUREMENTS
FAIR VALUE MEASUREMENTS	(10) FAIR VALUE MEASUREMENTS The Company’s financial instruments consist of cash and cash equivalents, restricted cash, trade receivables, accounts payable, long-term debt, certain post-employment plans and stock-based compensation liability. The carrying values of cash and cash equivalents, restricted cash, trade receivables and accounts payable approximated their fair values at December 31, 2017 and June 30, 2017 due to the short maturity of these instruments. The carrying value of the Company’s Notes, excluding debt issuance costs, reflects the original amounts borrowed, inclusive of net unamortized premium, and was $4,004.4 million and $3,692.8 million as of December 31, 2017 and June 30, 2017, respectively. Based on market interest rates for debt of similar terms and average maturities, the fair value of the Company's Notes as of December 31, 2017 and June 30, 2017 was estimated to be $4,108.4 million and $3,895.7 million, respectively. The Company’s fair value estimates associated with its Note obligations were derived utilizing Level 2 inputs—quoted prices for similar instruments in active markets. The carrying value of the Company’s Term Loan Facility, excluding debt issuance costs, reflects the original amounts borrowed, inclusive of unamortized discounts, and was $1,602.6 million and $1,912.7 million as of December 31, 2017 and June 30, 2017, respectively. The Company’s Term Loan Facility accrues interest at variable rates based upon the one-month, three-month or nine-month LIBOR plus i) a spread of 2.0% on the Company’s $500.0 million tranche (which has a LIBOR floor of 0.0%) and ii) a spread of 2.25% on its B-2 Term Loan tranche (which has a LIBOR floor of 1.00%) . Based on market interest rates for debt of similar terms and average maturities, the fair value of the Company’s Term Loan Facility as of December 31, 2017 and June 30, 2017 was estimated to be $1,622.4 million and $1,930.5 million, respectively. The Company’s fair value estimates associated with its Term Loan Facility obligations were derived utilizing Level 2 inputs—quoted prices for similar instruments in active markets. A hypothetical increase in the applicable interest rate on the Company’s Term Loan Facility of one percentage point above the 1.0% LIBOR floor would increase the Company’s annual interest expense by approximately $16.2 million. As of December 31, 2017 and June 30, 2017, there was no balance outstanding under the Company's Revolver.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Dec. 31, 2017
COMMITMENTS AND CONTINGENCIES
COMMITMENTS AND CONTINGENCIES	(11) COMMITMENTS AND CONTINGENCIES Purchase commitments At December 31, 2017, the Company was contractually committed for $408.4 million of capital expenditures for construction materials and purchases of property and equipment, as well as energy and network expenditures . A majority of these purchase commitments are expected to be satisfied in the next twelve months. These purchase commitments are primarily success based; that is, the Company has executed customer contracts that support the future capital expenditures. Outstanding Letters of Credit As of December 31, 2017, the Company had $8.0 million in outstanding letters of credit, which were primarily entered into in connection with various lease agreements. Additionally, as of December 31, 2017, Zayo Canada, Inc., a subsidiary of the Company, had CAD $3.5 million (or $2.8 million) in letters of credit, under a CAD $5.0 million (or $4.0 million) unsecured credit agreement. Contingencies In the normal course of business, the Company is party to various outstanding legal proceedings, asserted and unasserted claims, and carrier disputes. In the opinion of management, the ultimate disposition of these matters, both asserted and unasserted, will not have a material adverse effect on the Company’s financial condition, results of operations, or cash flows.

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	6 Months Ended
	Dec. 31, 2017
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS	(12) RELATED PARTY TRANSACTIONS In May 2016, CII sold Onvoy, LLC and its subsidiaries (“OVS”), a company that provided voice and managed offerings that the Company spun off during the year ended June 30, 2014, to an entity that has a material ownership interest in the Company. The Company continues to have ongoing contractual relationships with Inteliquent, Inc., successor by merger to OVS (“Inteliquent”), whereby the Company provides Inteliquent and its subsidiaries with bandwidth capacity and Inteliquent provides the Company and its subsidiaries with voice offerings. The contractual relationships are based on agreements that were entered into at estimated market rates. The following table represents the revenue and expense transactions the Company recorded with Inteliquent for the periods presented: Three Months Ended December 31, Six months ended December 31, 2017 2016 2017 2016 (in millions) Revenues $ 1.8 $ 1.5 $ 3.7 $ 3.1 Operating costs $ 0.6 $ 0.1 $ 1.2 $ 0.2 As of December 31, 2017 and June 30, 201 7 , the Company had $0.6 million and $0.5 million, respectively, due from Inteliquent. Dan Caruso, the Company’s Chief Executive Officer and Chairman of the Board, is a party to an aircraft charter (or membership) agreement through his affiliate, Bear Equity LLC, for business and personal travel. Under the terms of the charter agreement, all fees for the use of the aircraft are effectively variable in nature. For his business travel on behalf of the Company, Mr. Caruso is reimbursed for his use of the aircraft subject to an annual maximum reimbursement threshold approved by the Company's Nominating and Governance Committee. During the three and six months ended December 31, 2017 the Company reimbursed Mr. Caruso $0.2 million and $0.3 million, respectively, and during the three and six months ended December 31, 2016 reimbursed $0.2 million and $0. 4 million, respectively, for his business use of the aircraft.

SEGMENT REPORTING

SEGMENT REPORTING	6 Months Ended
	Dec. 31, 2017
SEGMENT REPORTING
SEGMENT REPORTING	(13) SEGMENT REPORTING The Company uses the management approach to determine the segment financial information that should be disaggregated and presented separately in the Company's notes to its financial statements. The management approach is based on the manner by which management has organized the segments within the Company for making operating decisions, allocating resources, and assessing performance. As the Company has increased in scope and scale, it has developed its management and reporting structure to support this growth. The Company’s bandwidth infrastructure, colocation and connectivity offerings are comprised of various related product groups generally defined around the type of offering to which the customer is licensing access, referred to as SPGs. Each SPG is responsible for the revenue, costs and associated capital expenditures of its respective solutions. The SPGs enable licensing and sales, make pricing and product decisions, engineer networks and deliver solutions to customers, and support customers for specific telecom and Internet infrastructure requirements. In connection with the Company’s continued increase in scope and scale, effective January 1, 2017, and in contemplation of the Company’s acquisition of Electric Lightwave which was completed March 1, 2017, the Company's chief operating decision maker ("CODM"), the Company's Chief Executive Officer, implemented certain organizational changes to the management and operation of the business that directly impact how the CODM makes resource allocation decisions and manages the Company. Under the new structure, the Company’s reportable segments include: Fiber Solutions, Transport, Enterprise Networks, Zayo Colocation, Allstream and Other. The change in structure had the impact of consolidating and/or regrouping existing SPGs and product offerings among the Company’s reportable segments and disaggregating the legacy Zayo Canada segment among the existing SPGs and a new Allstream reportable segment. The change in structure also resulted in adjustments to intercompany pricing that more closely align to third party pricing on the offerings that are provided between the Company’s SPGs. The Company’s legacy SPGs included Dark Fiber and Mobile Infrastructure Group (“MIG”). Effective January 1, 2017, the Dark Fiber and MIG SPGs were merged together and are now reported as part of the Fiber Solutions reporting segment. Waves and Ethernet solutions that are provided on dedicated dark fiber strands and colocation facilities that support only dark fiber customers, which were historically reported as part of the Waves, Ethernet or zColo SPGs, were transferred to the Fiber Solutions reportable segment effective January 1, 2017 (the “Dedicated Solutions Transfers”). The Company’s legacy Waves, IP and Sonet SPGs, after giving effect to the Dedicated Solutions Transfers, are now reported under the Company’s Transport reportable segment. The Company’s legacy Ethernet and Cloud SPGs, after giving effect to the Dedicated Solutions Transfers, are now reported under the Company’s Enterprise Networks segment. The Company’s legacy Zayo Canada reporting segment was disaggregated based upon the products offered by the legacy Zayo Canada segment to the Company’s existing SPGs and two new SPGs were established: Voice and Small and Medium Business (“SMB”). The Company’s segments are further described below: Fiber Solutions. Through the Fiber Solutions segment, the Company provides access to raw bandwidth infrastructure to customers that require more control of their internal networks. These solutions include dark fiber, dedicated lit networks and mobile infrastructure (fiber-to-the-tower and small cell). Dark fiber is a physically separate and secure, private platform for dedicated bandwidth. The Company leases dark fiber pairs (usually 2 to 12 total fibers) to its customers, who “light” the fiber using their own optronics. The Company’s mobile infrastructure solutions permit direct fiber connections to cell towers, small cells, hub sites, and mobile switching centers. Fiber Solutions customers include carriers and other communication service providers, Internet service providers, wireless service providers, major media and content companies, large enterprises, and other companies that have the expertise to run their own fiber optic networks or require interconnected technical space. The contract terms in the Fiber Solutions segment tend to range from three to twenty years. Transport. The Transport segment provides access to lit bandwidth infrastructure solutions over the Company’s metro, regional, and long-haul fiber networks. The segment uses customer-accessed optronics to light the fiber, and the Company’s customers pay for its offerings based on the amount and type of bandwidth access they acquire. The Company’s offerings within this segment include wavelengths, wholesale IP and SONET. The Company targets customers who require a minimum of 10G of bandwidth across their networks. Transport customers include carriers, content providers, financial services companies, healthcare, government entities, education institutions and other medium and large enterprises. The contract terms in this segment tend to range from two to five years. Enterprise Networks . The Enterprise Networks segment provides connectivity and lit bandwidth telecommunication solutions to medium and large enterprises. The Company’s offerings within this segment include Ethernet, enterprise private and connectivity products, managed products and cloud-based computing and storage products. Solutions range from point-to-point data connections to multi-site managed networks to international outsourced IT infrastructure environments. The contract terms in the Enterprise Networks segment tend to range from one to ten years. Zayo Colocation (zColo). The Colocation segment provides data center infrastructure solutions to a broad range of enterprise, carrier, cloud, and content customers. The Company’s offerings within this segment include the provision of colocation space, power and interconnection solutions in North America and Western Europe. Solutions range in size from single cabinet solutions to 1MW+ data center infrastructure environments. The Company’s data centers also support a large component of the Company’s networking components for the purpose of aggregating and accommodating data, voice, Internet, and video traffic. The contract terms in this segment tend to range from two to five years. Allstream. The Allstream segment provides Voice, SIP Trunking, Unified Communications and scalable data offerings using a variety of technologies for businesses. Voice provides a full range of local voice offerings allowing business customers to complete telephone calls in their local exchange, as well as make long distance, toll-free and related calls. Unified Communications is the integration of real-time communication functions such as telephony (including cloud-based IP telephony), instant messaging and video conferencing with non-real-time communication offerings, such as integrated voicemail and e-mail. Unified Communications provides a set of products that give users the ability to work and communicate across multiple components, media types and geographies. Allstream also offers a range of products that help small and medium business (“SMB”) customers implement the right data and networking solutions for their business. Those scalable products make use of technologies including Ethernet, IP/MPLS VPN Solutions, and wavelength solutions. Allstream provides support to customers in the SMB market while leveraging its extensive network and product offerings. These include IP, internet, voice, IP Trunking, cloud private branch exchange, collaboration offerings and unified communications. Other. The Other segment is primarily comprised of ZPS. ZPS provides network and technical resources to customers who wish to leverage our expertise in designing, acquiring and maintaining networks. The contract terms typically provide for a term of one year for a fixed recurring monthly fee in the case of network and on an hourly basis for technical resources (usage revenue). ZPS also generates revenue via telecommunication component sales. Effective January 1, 2017, revenues for all of the Company’s products are included in one of the Company’s six segments. This segment presentation has been recast for all periods presented for comparability. The results of operations for each segment include an allocation of certain indirect costs and corporate related costs, including overhead and third party-financed debt. The allocation is based on a percentage that represents management’s estimate of the relative burden each segment bears of indirect and corporate costs. Management has evaluated the allocation methods utilized to allocate these costs and determined they are systematic, rational and consistently applied. Identifiable assets for each reportable segment are reconciled to total consolidated assets including unallocated corporate assets and intersegment eliminations. Unallocated corporate assets consist primarily of cash and deferred taxes. Segment Adjusted EBITDA Segment Adjusted EBITDA is the primary measure used by the Company’s CODM to evaluate segment operating performance. The Company defines Segment Adjusted EBITDA as earnings/(loss) from operations before interest, income taxes, depreciation and amortization (“EBITDA”) adjusted to exclude acquisition or disposal-related transaction costs, losses on extinguishment of debt, stock-based compensation, unrealized foreign currency gains/(losses) on intercompany loans, and non-cash income/(loss) on equity and cost method investments. The Company uses Segment Adjusted EBITDA to evaluate operating performance, and this financial measure is among the primary measures used by management for planning and forecasting of future periods. The Company believes that the presentation of Segment Adjusted EBITDA is relevant and useful for investors because it allows investors to view results in a manner similar to the method used by management and facilitates comparison of the Company’s results with the results of other companies that have different financing and capital structures. Segment Adjusted EBITDA results, along with other quantitative and qualitative information, are also utilized by the Company and its Compensation Committee for purposes of determining bonus payouts to employees. Segment Adjusted EBITDA has limitations as an analytical tool and should not be considered in isolation from, or as a substitute for, analysis of the Company’s results from operations and operating cash flows as reported under GAAP. For example, Segment Adjusted EBITDA: · does not reflect capital expenditures, or future requirements for capital and major maintenance expenditures or contractual commitments; · does not reflect changes in, or cash requirements for, working capital needs; · does not reflect the significant interest expense, or the cash requirements necessary to service the interest payments, on the Company’s debt; and · does not reflect cash required to pay income taxes. The Company’s computation of Segment Adjusted EBITDA may not be comparable to other similarly titled measures computed by other companies because all companies do not calculate segment Adjusted EBITDA in the same fashion. For the three months ended December 31, 2017 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Revenue from external customers $ 200.5 $ 117.3 $ 145.9 $ 59.9 $ 123.5 $ 6.4 $ — $ 653.5 Segment Adjusted EBITDA 161.0 49.2 57.0 31.5 29.9 1.3 — 329.9 Capital expenditures 114.5 31.8 19.5 24.7 2.9 — — 193.4 As of and for the six months ended December 31, 2017 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Revenue from external customers $ 396.0 $ 236.4 $ 283.6 $ 118.3 $ 251.2 $ 11.5 $ — $ 1,297.0 Segment Adjusted EBITDA 315.2 100.8 106.5 60.9 60.7 2.4 — 646.5 Total assets 4,701.7 1,257.6 1,293.2 1,007.1 487.1 32.3 156.9 8,935.9 Capital expenditures 221.8 65.5 40.5 52.6 6.4 — — 386.8 For the three months ended December 31, 2016 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Revenue from external customers $ 177.5 $ 106.4 $ 114.7 $ 52.5 $ 51.6 $ 4.0 $ — $ 506.7 Segment Adjusted EBITDA 141.0 44.6 39.7 27.6 9.6 0.9 — 263.4 Capital expenditures 130.9 37.4 20.1 23.3 1.9 — — 213.6 For the six months ended December 31, 2016 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Revenue from external customers $ 351.6 $ 212.5 $ 229.1 $ 103.7 $ 106.1 $ 8.6 $ — $ 1,011.6 Segment Adjusted EBITDA 279.2 89.2 80.3 53.9 19.3 2.1 — 524.0 Capital expenditures 261.7 70.9 41.0 46.2 2.1 — — 421.9 As of June 30, 2017 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Total assets $ 4,504.6 $ 1,230.0 $ 1,385.7 $ 994.4 $ 406.2 $ 33.2 $ 185.3 $ 8,739.4 Reconciliation from Total Segment Adjusted EBITDA to income from operations before taxes: For the three months ended December 31, 2017 2016 (in millions) Total Segment Adjusted EBITDA $ 329.9 $ 263.4 Interest expense (73.1) (53.7) Depreciation and amortization expense (195.9) (131.4) Transaction costs (5.9) (6.2) Stock-based compensation (23.5) (34.5) Foreign currency gain/(loss) on intercompany loans 3.1 (17.4) Non-cash loss on investments (0.2) (0.2) Income from operations before income taxes $ 34.4 $ 20.0 For the six months ended December 31, 2017 2016 (in millions) Total Segment Adjusted EBITDA $ 646.5 $ 524.0 Interest expense (146.7) (107.0) Depreciation and amortization expense (380.0) (269.9) Transaction costs (14.2) (9.2) Stock-based compensation (51.3) (66.5) Loss on extinguishment of debt (4.9) — Foreign currency gain/(loss) on intercompany loans 13.9 (28.6) Non-cash loss on investments (0.3) (0.5) Income from operations before income taxes $ 63.0 $ 42.3

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	6 Months Ended
	Dec. 31, 2017
SUBSEQUENT EVENTS
SUBSEQUENT EVENTS	(14) SUBSEQUENT EVENTS On January 18, 2018, the Company completed the CAD $31.0 million (or $24.9 million) cash acquisition of Vancouver-based Optic Zoo Networks. Optic Zoo Networks owns and provides access to high-capacity fiber in Vancouver and has achieved a significant penetration of customers, with a focus on the digital media sector. The transaction adds 103 route miles and more than 100 on-net buildings to the Company’s Vancouver footprint. The acquisition will be accounted for as a business combination using the acquisition method of accounting, whereby the total purchase price will be allocated to the acquired identifiable net assets based on assessments of their respective fair values, and the excess of the purchase price over the fair values of these identifiable net assets will be allocated to goodwill. Due to the timing of the transaction, the initial accounting for this acquisition, including the measurement of assets acquired, liabilities assumed and goodwill, has not yet been determined and is pending detailed analyses of the facts and circumstances that existed as of the January 18, 2018 acquisition date. On January 28, 2018, the Company entered into an agreement to acquire substantially all of the assets of Neutral Path Communications and Near North Partners for $31.5 million. The purchase price is subject to net working capital and other customary adjustments, as well as a contingent payment based on sales performance through June 30, 2018. Neutral Path is a long haul infrastructure provider, providing access to a fiber network in the Midwest. The transaction will add 452 owned plus additional leased route miles to the Company’s extensive North American network, including a unique, high-count fiber route from Minneapolis to Omaha.

BUSINESS AND BASIS OF PRESENT22

BUSINESS AND BASIS OF PRESENTATION (Policies)	6 Months Ended
	Dec. 31, 2017
BUSINESS AND BASIS OF PRESENTATION
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements include all the accounts of the Company and its wholly-owned subsidiaries. All inter-company accounts and transactions have been eliminated in consolidation. The accompanying condensed consolidated financial statements and related notes are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial reporting and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for quarterly reports on Form 10-Q, and do not include all of the note disclosures required by GAAP for complete financial statements. These condensed consolidated financial statements should, therefore, be read in conjunction with the consolidated financial statements and notes thereto for the year ended June 30, 2017 included in the Company’s Annual Report on Form 10-K for the year ended June 30, 2017. In the opinion of management, all adjustments considered necessary for a fair presentation of financial position, results of operations and cash flows of the Company have been included herein. The results of operations for the three and six months ended December 31, 2017 are not necessarily indicative of the operating results for any future interim period or the full year. The Company’s fiscal year ends June 30 each year, and we refer to the fiscal year ending June 30, 2019 as “Fiscal 2019”, the fiscal year ending June 30, 2018 as “Fiscal 2018” and the fiscal year ended June 30, 2017 as “Fiscal 2017.”
Earnings per Share	Earnings per Share Basic earnings per share attributable to the Company’s common shareholders is computed by dividing net earnings attributable to common shareholders by the weighted average number of common shares outstanding for the period. Diluted earnings per share attributable to common shareholders presents the dilutive effect, if any, on a per share basis of potential common shares (such as restricted stock units) as if they had been vested or converted during the periods presented. The Company’s computation of diluted income per share for the three and six months ended December 31, 2017 included an adjustment of 1. 9 million and 2. 3 million shares, respectively, and for the three and six months ended December 31, 2016 included an adjustment of 2.5 million and 2.0 million shares, respectively, to the weighted-average shares to account for the dilutive effect of the Part A and Part B restricted stock units (“RSUs”) and related issuance of common shares upon vesting (see Note 8 – Stock-based Compensation ) (calculated using the treasury method).
Significant Accounting Policies	Significant Accounting Policies the Company acquired defined benefit pension plans and other non-pension post-retirement benefits (“OPEBs”) that cover qualifying foreign employees. The pension plans and OPEBs were legally transferred to the Company during the three months ended December 31, 2017. Eligibility and the level of benefits for these plans varies depending on participants’ status, date of hire and or length of service. The Company recognizes the funded status of these defined benefit and post-retirement plans as an asset or a liability on the condensed consolidated balance sheet. Each year's actuarial gains or losses and prior period service costs are a component of other comprehensive income/(loss), which is then included in accumulated other comprehensive income. Pension and post-retirement benefit expenses are recognized over the period in which the employee renders service and becomes eligible to receive benefits. The pension and post-retirement accruals and valuations are dependent on actuarial assumptions to calculate those amounts. These assumptions include discount rates, long-term rate of return on plan assets, retirement rates, mortality rates and other factors. A change in any of the above assumptions would have an effect on the projected benefit obligation and pension expense. See Note 9 – Employee Benefits , for additional disclosure regarding the Company’s defined benefit pension plans and OPEBs. The Company’s policy is to fund the pension plans in accordance with applicable regulations. The OPEBs are not funded. There have been no other changes to the Company’s significant accounting policies described in its Annual Report on Form 10-K for the year ended June 30, 2017.
Use of Estimates	Use of Estimates The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expense during the reporting period. Significant estimates are used when establishing allowances for doubtful accounts and accruals for billing disputes, determining useful lives for depreciation and amortization and accruals for exit activities associated with real estate leases, assessing the need for impairment charges (including those related to intangible assets and goodwill), determining the fair values of assets acquired and liabilities assumed in business combinations, accounting for income taxes and related valuation allowances against deferred tax assets, determining the defined benefit costs and defined benefit obligations related to post-employment benefits, determining the fair value of plan assets related to post-employment benefits and estimating certain restricted stock unit grant fair values used to compute the stock-based compensation liability and expense. Management evaluates these estimates and judgments on an ongoing basis and makes estimates based on historical experience, current conditions, and various other assumptions that are believed to be reasonable under the circumstances. The results of these estimates form the basis for making judgments about the carrying values of assets and liabilities as well as identifying and assessing the accounting treatment with respect to commitments and contingencies. Actual results may differ from these estimates under different assumptions or conditions.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In March 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2017-07, Compensation – Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost . This ASU requires an employer to report the service cost component of net periodic pension cost and net periodic postretirement cost in the same line item in the statement of operations as other compensation costs arising from services rendered by the related employees during the period. The other net cost components are required to be presented in the statement of operations separately from the service cost component and outside a subtotal of income from operations. Additionally, the line item used in the statement of operations to present the other net cost components must be disclosed in the notes to the financial statements. This ASU is effective for fiscal years beginning after December 15, 2017 (Fiscal 2019 for the Company), and interim periods within those fiscal years, and must be applied on a retrospective basis. Had the Company adopted this ASU in the quarter it would not have resulted in a material impact to the financial statements for the three and six months ended December 31, 2017. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classifications of Certain Cash Receipts and Cash Payments. The new standard provides guidance for eight changes with respect to how cash receipts and cash payments are classified in the statement of cash flows, with the objective of reducing diversity in practice. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 31, 2017 (Fiscal 2019 for the Company), with early adoption permitted. The Company does not plan to early adopt, nor does it expect the adoption of this new standard to have a material impact on its condensed consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases . The new guidance supersedes existing guidance on accounting for leases in Topic 840 and is intended to increase the transparency and comparability of accounting for lease transactions. ASU 2016-02 requires most leases to be recognized on the balance sheet. Lessees will need to recognize a right-of-use asset and a lease liability for virtually all leases. The liability will be equal to the present value of lease payments. The asset will be based on the liability, subject to adjustment, such as for initial direct costs. For income statement purposes, the FASB retained a dual model, requiring leases to be classified as either operating or finance. Lessor accounting remains similar to the current model, but updated to align with certain changes to the lessee model and the new revenue recognition standard (ASU 2014-09). The ASU will require both quantitative and qualitative disclosures regarding key information about leasing arrangements. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018 (Fiscal 2020 for the Company) . Early adoption is permitted. The standard must be adopted using a modified retrospective transition, and provides for certain practical expedients. Transition will require application of the new guidance at the beginning of the earliest comparative period presented. The Company established a project team and commenced an initial impact assessment process. To date, the Company has reviewed a sample of lessee and lessor arrangements and made preliminary assessments of the impact this standard will have on the consolidated financial statements. Although it is still assessing the impact of this standard, the Company expects the new guidance to significantly increase the reported assets and liabilities on the consolidated balance sheets. There are currently no plans to early adopt this ASU. In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers , which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance under GAAP when it becomes effective. In July 2015, the FASB deferred the effective date to annual reporting periods and interim reporting periods within annual reporting periods beginning after December 15, 2017 (Fiscal 2019 for the Company) . Early adoption was permitted as of the original effective date or annual reporting periods and interim reporting periods within annual reporting periods beginning after December 15, 2016. The standard permits the use of either the retrospective or cumulative effect transition method . In Fiscal 2017, the Company established a project team and commenced an initial assessment to determine the impact ASU 2014-09 will have on the Company’s revenue arrangements. Lease revenue is not included in the scope of ASU 2014-09, and as a result, the revenue to which the Company must apply the new guidance is generally limited to solutions revenue, certain maintenance revenue not covered by lease arrangements, certain transactions that include the title transfer of integral components to customers and other fees charged to customers. Although the Company is still assessing the impact of this standard on its consolidated financial statements, it has preliminarily determined that due to changes in the timing of recognition of certain installations, discounts and promotional credits given to customers, there may be additional contract assets and liabilities recorded in the consolidated balance sheets upon adoption. Additionally, the requirement to defer incremental costs incurred to acquire a contract including sales commissions, and recognize such costs over the contract period or expected customer life may result in additional deferred charges recognized in the consolidated balance sheets and could have the impact of deferring operating expenses. The assessment of the impact of this standard on the Company’s consolidated financial statements also includes developing new accounting policies, internal controls and procedures and possible changes to our systems to facilitate the adoption of this accounting policy. The Company will adopt this new standard as of July 1, 2018 and, based on its current assessment, expects to apply the modified retrospective method, which may result in a cumulative effect adjustment as of the date of adoption. The Company's initial assessment of changes to the reporting of its revenue and expenses and anticipated adoption method may change depending on the results of the Company’s ongoing and final assessment of this ASU. Until the Company is further along in its assessment, it does not anticipate being able to provide reasonably accurate estimates of the impact of ASU 2014-09

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	6 Months Ended
	Dec. 31, 2017
ACQUISITIONS
Schedule of Acquisitions	The table below reflects the Company's estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2017 acquisitions: KIO Networks US Data Centers Electric Lightwave Santa Clara Data Acquisition date May 1, 2017 March 1, 2017 October 3, 2016 (in millions) Cash $ 0.1 $ 12.6 $ — Other current assets 0.1 55.0 — Property and equipment 2.4 572.8 31.9 Deferred tax assets, net 1.8 — — Intangibles 6.4 472.4 6.0 Goodwill 2.9 498.4 — Other assets 0.5 1.7 — Total assets acquired 14.2 1,612.9 37.9 Current liabilities 1.7 57.4 — Deferred tax liabilities, net — 35.1 — Capital lease obligations — — 26.6 Deferred revenue 0.5 80.0 — Other liabilities — 1.2 — Total liabilities assumed 2.2 173.7 26.6 Net assets acquired 12.0 1,439.2 11.3 Less cash acquired (0.1) (12.6) — Total consideration paid/payable $ 11.9 $ 1,426.6 $ 11.3

GOODWILL (Tables)

GOODWILL (Tables)	6 Months Ended
	Dec. 31, 2017
GOODWILL
Schedule of Goodwill	Product Group As of June 30, 2017 Adjustments to Fiscal 2017 Foreign Currency As of December 31, 2017 (in millions) Fiber Solutions $ 633.9 $ 145.5 $ 3.1 $ 782.5 Waves 247.4 (62.3) 1.6 186.7 Sonet 52.0 30.9 0.1 83.0 Ethernet 359.5 (263.6) 0.2 96.1 EPIC 89.5 80.0 0.3 169.8 zColo 256.3 2.7 1.3 260.3 Cloud 69.5 (4.9) 0.1 64.7 Allstream 116.5 (62.3) — 54.2 Other 15.6 — 15.6 Total $ 1,840.2 $ (134.0) $ 6.7 $ 1,712.9

INTANGIBLE ASSETS (Tables)

INTANGIBLE ASSETS (Tables)	6 Months Ended
	Dec. 31, 2017
INTANGIBLE ASSETS
Schedule of Identifiable Acquisition Related Intangible Assets	Gross Carrying Amount Accumulated Net (in millions) December 31, 2017 Finite-Lived Intangible Assets Customer relationships $ 1,643.9 $ (361.1) $ 1,282.8 Underlying rights 1.6 (0.5) 1.1 Total 1,645.5 (361.6) 1,283.9 Indefinite-Lived Intangible Assets Certifications 3.5 — 3.5 Underlying Rights 15.4 — 15.4 Total $ 1,664.4 $ (361.6) $ 1,302.8 June 30, 2017 Finite-Lived Intangible Assets Customer relationships $ 1,477.7 $ (308.6) $ 1,169.1 Underlying rights 1.6 (0.4) 1.2 Total 1,479.3 (309.0) 1,170.3 Indefinite-Lived Intangible Assets Certifications 3.5 — 3.5 Underlying Rights 14.8 — 14.8 Total $ 1,497.6 $ (309.0) $ 1,188.6

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	6 Months Ended
	Dec. 31, 2017
LONG-TERM DEBT
Schedule of Debt	Date of Outstanding as of Issuance or most Maturity Interest Interest Rate December 31, June 30, (in millions) Term Loan Facility due 2021 Jan 2017 Jan 2021 Monthly LIBOR +2.00% $ 496.3 $ 498.8 B-2 Term Loan Facility Jul 2017 Jan 2024 Monthly LIBOR +2.25% 1,119.3 1,429.9 6.00% Senior Unsecured Notes Jan & Mar 2015 Apr 2023 Apr/Oct 6.00% 1,430.0 1,430.0 6.375% Senior Unsecured Notes May 2015 & Apr 2016 May 2025 May/Nov 6.375% 900.0 900.0 5.75% Senior Unsecured Notes Jan, Apr & Jul 2017 Jan 2027 Jan/Ju1 5.75% 1,650.0 1,350.0 Total obligations 5,595.6 5,608.7 Unamortized premium/(discounts), net 11.4 (3.2) Unamortized debt issuance costs (63.4) (67.8) Carrying value of debt 5,543.6 5,537.7 Less current portion (5.0) (5.0) Total long-term debt, less current portion $ 5,538.6 $ 5,532.7

INCOME TAXES (Tables)

INCOME TAXES (Tables)	6 Months Ended
	Dec. 31, 2017
INCOME TAXES
Schedule of Reconciliation of Income Tax Provision	Three months ended December 31, Six months ended December 31, 2017 2016 2017 2016 (in millions) Expected provision at the statutory rate $ 7.6 $ 7.1 $ 17.6 $ 14.8 Increase/(decrease) due to: State income tax expense, net of federal benefit 0.9 0.8 1.5 1.5 Stock-based compensation 1.0 (2.9) 2.5 0.4 Transactions costs not deductible for tax purposes 0.1 0.2 0.2 0.3 Change in statutory tax rate, non-U.S. 0.8 — 0.8 (1.7) Foreign tax rate differential 0.5 0.4 (1.7) (0.3) Change in valuation allowance (25.7) (4.4) (31.4) (6.7) U.S. Tax Reform 44.1 — 44.1 — Other, net (6.4) (1.0) (5.3) (1.5) Provision for income taxes $ 22.9 $ 0.2 $ 28.3 $ 6.8
Schedule Provisional amounts recognized for income taxes	Provisional amounts recognized due to the U.S. Tax Reform for the three and six months ended December 31, 2017: Tax Expense Deferred Tax Liability Current Tax Receivable (in millions) Change in statutory tax rate, U.S. only (AMT credit is now refundable) $ 1.4 $ 11.4 $ 10.0 Changes to indefinite reinvestment assertion 7.9 7.9 Repatriation Tax (offset against net operating loss carryforwards, non-cash) 34.8 34.8 Net discrete impacts of the enactment of U.S. Tax Reform $ 44.1 $ 54.1 $ 10.0
Schedule of statutory tax rate for determining provision for tax table text block	Fiscal 2017 Fiscal 2018 Fiscal 2019 Tax Rates Federal Rate 35% 28% 21% Blended Federal & State Rate 39% 33% 26%

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	6 Months Ended
	Dec. 31, 2017
Schedule of Employee Service Share-based Compensation Allocation of Recognized Period Costs	Three months ended December 31, Six months ended December 31, 2017 2016 2017 2016 (in millions) Included in: Operating costs $ 2.3 $ 3.3 $ 5.5 $ 6.6 Selling, general and administrative expenses 21.2 31.2 45.8 59.9 Total stock-based compensation expense $ 23.5 $ 34.5 $ 51.3 $ 66.5 CII common units $ — $ 5.9 $ — $ 10.1 Part A restricted stock units 19.4 18.8 41.6 40.1 Part B restricted stock units 3.6 9.5 8.7 15.7 Part C restricted stock units 0.5 0.3 1.0 0.6 Total stock-based compensation expense $ 23.5 $ 34.5 $ 51.3 $ 66.5
Summary Of Part B RSU Issuance	During the three months ended December 31, September 30, Part B RSUs granted 82,556 163,960 Maximum eligible shares of the Company's common stock 569,636 590,256 Grant date fair value per Part B RSU $ $ Units converted to Company's common stock at vesting date n/a n/a During the three months ended June 30, 2017 March 31, 2017 December 31, 2016 September 30, 2016 Part B RSUs granted 152,808 171,316 191,015 200,425 Maximum eligible shares of the Company's common stock 550,109 880,564 981,817 1,030,185 Grant date fair value per Part B RSU $ 26.52 $ 27.39 $ 75.56 $ 47.00 Units converted to Company's common stock at vesting date n/a 41,368 102,511 99,508
Part A Restricted Stock Units [Member]
Summary Of Restricted Stock Units Activity	The following table summarizes the Company’s Part A RSU activity for the six months ended December 31, 2017: Number of Part A Weighted average Weighted average Outstanding at July 1, 2017 2,364,386 $ 31.63 7.1 Granted 1,158,872 34.96 Vested (1,460,389) 31.54 Forfeited (193,105) n/a Outstanding at December 31, 2017 1,869,764 $ 33.42 7.4
Part B Restricted Stock Units [Member]
Summary Of Restricted Stock Units Activity	The following table summarizes the Company’s Part B RSU activity for the six months ended December 31, 2017: Number of Part B Weighted average Weighted average Outstanding at July 1, 2017 411,973 $ 42.86 6.1 Granted 246,516 27.28 Vested (252,529) 52.49 Forfeited (6,636) n/a Outstanding at December 31, 2017 399,324 $ 27.30 6.0

EMPLOYEE BENEFITS (Tables)

EMPLOYEE BENEFITS (Tables)	6 Months Ended
	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of changes in benefit obligations, fair value of plan assets and the underfunded status for the Company's defined benefit pension and postretirement benefit plans	Pension Plans (in millions) Change in pension plan assets Fair value of plan assets at July 1, 2017 $ 3.7 Return on plan assets 1.2 Employer contributions 1.6 Participant contributions 0.3 Benefits paid from plan assets (3.6) Acquisition transfer 93.9 Foreign currency exchange rate changes 0.1 Fair value of pension plan assets at December 31, 2017 $ 97.2 Pension Plans As of December 31, 2017 (in millions) Projected benefit obligation $ 106.6 Fair value of plan assets 97.2 Unfunded status 9.4 Current portion of unfunded status $ — Non-current portion of unfunded status $ 9.4
Schedule of accumulated other comprehensive loss ("AOCI") that have not yet been recognized as components of net periodic benefit cost	As of June 30, 2017 Deferrals Net Change in AOCI As of December 31, 2017 (in millions) Accumulated other comprehensive loss: Pension plans: Net actuarial (loss)/gain $ — $ 1.3 $ 1.3 $ 1.3 Prior service benefit/(cost) — (8.0) (8.0) (8.0) Deferred income tax benefit/(expense) — 1.7 1.7 1.7 Total pension plans — (5.0) (5.0) (5.0) Post-retirement benefit plans: Net actuarial (loss)/gain (1.2) — — (1.2) Prior service (cost)/benefit — — — — Deferred income tax benefit/(expense) 0.4 — — 0.4 Total post-retirement benefit plans (0.8) — — (0.8) Total accumulated other comprehensive loss $ (0.8) $ (5.0) $ (5.0) $ (5.8)
Schedule of expected benefit payments for the Company's defined benefit pension and OPEB plans	Post-Retirement Pension Plans Benefit Plans (in millions) Year ended June 30, 2018 $ 2.8 $ 0.6 2019 3.0 0.6 2020 3.2 0.6 2021 3.5 0.5 2022 3.7 0.5 2023-2027 22.6 2.5
Schedule of assumptions used in determining benefit obligations	Pension Plans OPEB Plans Actuarial assumptions: Discount rate Price inflation N/A Expected long-term rate of return on plan assets N/A Rate of compensation increase 2% plus merit & promotion N/A
Schedule of targets for the allocation of invested defined benefit pension plan assets and fair value of plan assets	The following table presents the Company’s target for the allocation of invested defined benefit pension plan assets at December 31, 2017: As of December 31, 2017 Fixed income Equities Other Total The plans assets are invested in various fund categories utilizing multiple strategies and investment managers. Interests in funds are valued using the net asset value ("NAV") per unit of each fund. The NAV reported by the fund manager is based on the market value of the underlying investments owned by each fund, minus its liabilities, divided by the number of shares outstanding. These funds can be redeemed at NAV, generally at any time. As the funds do not publish publicly available prices, the NAV practical expedient is the most appropriate fair value classification for the plan asset investments. The value associated with these investments is disclosed in the reconciliation of the total investments measured at fair value shown below. The table below presents the fair value of plan assets valued at NAV by category for the pension and post-retirement plans at December 31, 2017. As of December 31, 2017 (in millions) Fixed income $ 36.3 Equities 55.9 Other 5.0 Total $ 97.2
Pension Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of changes in benefit obligations, fair value of plan assets and the underfunded status for the Company's defined benefit pension and postretirement benefit plans	Pension Plans (in millions) Change in projected benefit obligation for defined benefit pension plans: Projected benefit obligation at July 1, 2017 $ 6.7 Service cost 1.5 Interest cost 0.7 Actuarial loss (gain) (1.3) Participant contributions 0.3 Benefits paid from plan assets (3.6) Acquisition transfer 102.1 Foreign currency exchange rate changes 0.2 Projected benefit obligation at December 31, 2017 $ 106.6
Schedule of net periodic (benefit) cost of the defined benefit pension and OPEB is included in selling, general and administrative expenses	Pension Plans Three months ended December 31, 2017 Six months ended December 31, 2017 ( in millions) Service cost $ 0.7 $ 1.5 Interest cost 0.6 0.7 Expected return on plan assets (1.0) (1.1) Net periodic pension benefit income $ 0.3 $ 1.1
Post-Retirement Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of changes in benefit obligations, fair value of plan assets and the underfunded status for the Company's defined benefit pension and postretirement benefit plans	Post-Retirement Benefit Plans (in millions) Change in projected benefit obligation for OPEB plans Projected benefit obligation at July 1, 2017 $ 9.9 Service cost 0.1 Interest cost 0.2 Benefits paid by Company (0.3) Foreign currency exchange rate changes 0.2 Projected benefit obligation at December 31, 2017 $ 10.1
Schedule of net periodic (benefit) cost of the defined benefit pension and OPEB is included in selling, general and administrative expenses	OPEB Plans Three months ended December 31, 2017 Six months ended December 31, 2017 (in millions) Service cost $ — $ 0.1 Interest cost 0.1 0.2 Net periodic post-retirement benefit income $ 0.1 $ 0.3

RELATED PARTY TRANSACTIONS (Tab

RELATED PARTY TRANSACTIONS (Tables)	6 Months Ended
	Dec. 31, 2017
RELATED PARTY TRANSACTIONS
Revenue and Expense Transactions Recognized	Three Months Ended December 31, Six months ended December 31, 2017 2016 2017 2016 (in millions) Revenues $ 1.8 $ 1.5 $ 3.7 $ 3.1 Operating costs $ 0.6 $ 0.1 $ 1.2 $ 0.2

SEGMENT REPORTING (Tables)

SEGMENT REPORTING (Tables)	6 Months Ended
	Dec. 31, 2017
SEGMENT REPORTING
Summary of Financial Information by Segments	For the three months ended December 31, 2017 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Revenue from external customers $ 200.5 $ 117.3 $ 145.9 $ 59.9 $ 123.5 $ 6.4 $ — $ 653.5 Segment Adjusted EBITDA 161.0 49.2 57.0 31.5 29.9 1.3 — 329.9 Capital expenditures 114.5 31.8 19.5 24.7 2.9 — — 193.4 As of and for the six months ended December 31, 2017 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Revenue from external customers $ 396.0 $ 236.4 $ 283.6 $ 118.3 $ 251.2 $ 11.5 $ — $ 1,297.0 Segment Adjusted EBITDA 315.2 100.8 106.5 60.9 60.7 2.4 — 646.5 Total assets 4,701.7 1,257.6 1,293.2 1,007.1 487.1 32.3 156.9 8,935.9 Capital expenditures 221.8 65.5 40.5 52.6 6.4 — — 386.8 For the three months ended December 31, 2016 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Revenue from external customers $ 177.5 $ 106.4 $ 114.7 $ 52.5 $ 51.6 $ 4.0 $ — $ 506.7 Segment Adjusted EBITDA 141.0 44.6 39.7 27.6 9.6 0.9 — 263.4 Capital expenditures 130.9 37.4 20.1 23.3 1.9 — — 213.6 For the six months ended December 31, 2016 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Revenue from external customers $ 351.6 $ 212.5 $ 229.1 $ 103.7 $ 106.1 $ 8.6 $ — $ 1,011.6 Segment Adjusted EBITDA 279.2 89.2 80.3 53.9 19.3 2.1 — 524.0 Capital expenditures 261.7 70.9 41.0 46.2 2.1 — — 421.9 As of June 30, 2017 Fiber Transport Enterprise zColo Allstream Other Corp/ Total (in millions) Total assets $ 4,504.6 $ 1,230.0 $ 1,385.7 $ 994.4 $ 406.2 $ 33.2 $ 185.3 $ 8,739.4
Reconciliation from Total Segment Adjusted EBITDA to income/(loss) from operations before taxes	For the three months ended December 31, 2017 2016 (in millions) Total Segment Adjusted EBITDA $ 329.9 $ 263.4 Interest expense (73.1) (53.7) Depreciation and amortization expense (195.9) (131.4) Transaction costs (5.9) (6.2) Stock-based compensation (23.5) (34.5) Foreign currency gain/(loss) on intercompany loans 3.1 (17.4) Non-cash loss on investments (0.2) (0.2) Income from operations before income taxes $ 34.4 $ 20.0 For the six months ended December 31, 2017 2016 (in millions) Total Segment Adjusted EBITDA $ 646.5 $ 524.0 Interest expense (146.7) (107.0) Depreciation and amortization expense (380.0) (269.9) Transaction costs (14.2) (9.2) Stock-based compensation (51.3) (66.5) Loss on extinguishment of debt (4.9) — Foreign currency gain/(loss) on intercompany loans 13.9 (28.6) Non-cash loss on investments (0.3) (0.5) Income from operations before income taxes $ 63.0 $ 42.3

BUSINESS AND BASIS OF PRESENT32

BUSINESS AND BASIS OF PRESENTATION (Details) - shares shares in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Basis Of Presentation And Significant Accounting Policies [Line Items]
Weighted-average shares included to account for the dilutive effect of the Part A and Part B RSUs	1.9	2.5	2.3	2
Allstream
Basis Of Presentation And Significant Accounting Policies [Line Items]
Percentage of entity acquired	100.00%		100.00%

ACQUISITIONS (Narrative) (Detai

ACQUISITIONS (Narrative) (Details) $ in Millions	Nov. 26, 2017USD ($)mi	May 01, 2017USD ($)ft²CenterMW	Mar. 01, 2017USD ($)buildingitemmiCenter	Oct. 03, 2016USD ($)ft²itemMW	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2017USD ($)item	Sep. 30, 2017USD ($)	Dec. 31, 2016USD ($)
Business Acquisition [Line Items]
Number of business combinations completed | item								41
Increase in intangible assets					$ 160.2
Increase in property plant and equipment					52.2
Decrease in deferred tax assets								$ 80.2
Decrease in depreciation and amortization					(12.1)	$ (12.1)
Decrease in depreciation and amortization early reported						$ 8.4			$ 4.8
Acquisition related costs					$ 5.9		$ 6.2	14.2		$ 9.2
Net consideration paid										$ 1.3
Spread Networks
Business Acquisition [Line Items]
Business acquisition purchase price	$ 127
Spread Networks | Long Haul Fiber [Member]
Business Acquisition [Line Items]
Additional Route Miles Acquired | mi	825
KIO Networks US Data Centers
Business Acquisition [Line Items]
Business acquisition purchase price		$ 11.9
Acquired facility size (in square feet) | ft²		100,000
Acquired megawatts of critical power | MW		2
Purchase price, held in escrow		$ 1.2
Number of data centers | Center		2
Electric Lightwave
Business Acquisition [Line Items]
Business acquisition purchase price			$ 1,426.6
Purchase price, held in escrow			$ 7
Number of metropolitan markets | item			35
Net Buildings Concentrating Network | building			3,100
Number of data centers | Center			100
Net consideration paid			$ 1,426.6
Electric Lightwave | Long Haul Fiber [Member]
Business Acquisition [Line Items]
Additional Route Miles Acquired | mi			8,100
Electric Lightwave | Metro Fiber [Member]
Business Acquisition [Line Items]
Additional Route Miles Acquired | mi			4,000
Santa Clara Data Center
Business Acquisition [Line Items]
Business acquisition purchase price				$ 11.3
Acquired facility size (in square feet) | ft²				26,900
Acquired megawatts of critical power | MW				3
Remaining cash consideration to be paid				$ 6.4
Number of quarterly payments | item				10
Amount of quarterly payments				$ 1.3				$ 2.5

ACQUISITIONS (Schedule of Acqui

ACQUISITIONS (Schedule of Acquisition) (Details) - USD ($) $ in Millions	May 01, 2017	Mar. 01, 2017	Oct. 03, 2016	Dec. 31, 2017	Jun. 30, 2017
Business Acquisition [Line Items]
Goodwill				$ 1,712.9	$ 1,840.2
KIO Networks US Data Centers
Business Acquisition [Line Items]
Cash	$ 0.1
Other current assets	0.1
Property and equipment	2.4
Deferred tax assets, net	1.8
Intangibles	6.4
Goodwill	2.9
Other assets	0.5
Total assets acquired	14.2
Current liabilities	1.7
Deferred revenue	0.5
Total liabilities assumed	2.2
Net assets acquired	12
Less cash acquired	(0.1)
Total consideration paid/payable	$ 11.9
Electric Lightwave
Business Acquisition [Line Items]
Cash		$ 12.6
Other current assets		55
Property and equipment		572.8
Intangibles		472.4
Goodwill		498.4
Other assets		1.7
Total assets acquired		1,612.9
Current liabilities		57.4
Deferred tax liability, net		35.1
Deferred revenue		80
Other liabilities		1.2
Total liabilities assumed		173.7
Net assets acquired		1,439.2
Less cash acquired		(12.6)
Total consideration paid/payable		$ 1,426.6
Santa Clara Data Center
Business Acquisition [Line Items]
Property and equipment			$ 31.9
Intangibles			6
Total assets acquired			37.9
Capital lease obligations			26.6
Total liabilities assumed			26.6
Net assets acquired			11.3
Total consideration paid/payable			$ 11.3

GOODWILL (Schedule Of Goodwill)

GOODWILL (Schedule Of Goodwill) (Details) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Dec. 31, 2017	Jun. 30, 2017
Goodwill [Line Items]
Goodwill, beginning Balance	$ 1,840.2
Adjustments to Fiscal Acquisitions		$ (134)
Foreign Currency Translation and Other	6.7
Goodwill, ending balance	1,712.9	1,840.2
Fiber Solutions [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	633.9
Adjustments to Fiscal Acquisitions		145.5
Foreign Currency Translation and Other	3.1
Goodwill, ending balance	782.5	633.9
Waves [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	247.4
Adjustments to Fiscal Acquisitions		(62.3)
Foreign Currency Translation and Other	1.6
Goodwill, ending balance	186.7	247.4
Sonet [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	52
Adjustments to Fiscal Acquisitions		30.9
Foreign Currency Translation and Other	0.1
Goodwill, ending balance	83	52
Ethernet [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	359.5
Adjustments to Fiscal Acquisitions		(263.6)
Foreign Currency Translation and Other	0.2
Goodwill, ending balance	96.1	359.5
EPIC [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	89.5
Adjustments to Fiscal Acquisitions		80
Foreign Currency Translation and Other	0.3
Goodwill, ending balance	169.8	89.5
zColo [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	256.3
Adjustments to Fiscal Acquisitions		2.7
Foreign Currency Translation and Other	1.3
Goodwill, ending balance	260.3	256.3
Cloud [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	69.5
Adjustments to Fiscal Acquisitions		(4.9)
Foreign Currency Translation and Other	0.1
Goodwill, ending balance	64.7	69.5
Allstream
Goodwill [Line Items]
Goodwill, beginning Balance	116.5
Adjustments to Fiscal Acquisitions		(62.3)
Goodwill, ending balance	54.2	116.5
Other [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	15.6
Goodwill, ending balance	$ 15.6	$ 15.6

INTANGIBLE ASSETS (Schedule of

INTANGIBLE ASSETS (Schedule of Identifiable Acquisition Related Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Jun. 30, 2017
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount	$ 1,645.5	$ 1,479.3
Accumulated Amortization	(361.6)	(309)
Total Net	1,283.9	1,170.3
Gross Carrying Amount, Indefinite-lived Intangibles	1,664.4	1,497.6
Intangible Assets, Net	1,302.8	1,188.6
Certifications [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount, Indefinite-lived Intangibles	3.5	3.5
Intangible Assets, Net	3.5	3.5
Indefinite-Lived Underlying Rights [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount, Indefinite-lived Intangibles	15.4	14.8
Intangible Assets, Net	15.4	14.8
Customer relationships [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount	1,643.9	1,477.7
Accumulated Amortization	(361.1)	(308.6)
Total Net	1,282.8	1,169.1
Finite-Lived Underlying rights [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount	1.6	1.6
Accumulated Amortization	(0.5)	(0.4)
Total Net	$ 1.1	$ 1.2

LONG-TERM DEBT (Summary of Long

LONG-TERM DEBT (Summary of Long-Term Debt) (Details) - USD ($) $ in Millions	Jul. 22, 2016	Dec. 31, 2017	Jun. 30, 2017	Jul. 05, 2017	Apr. 10, 2017	Jan. 27, 2017	Jan. 19, 2017
Debt Instrument [Line Items]
Debt obligations		$ 5,595.6	$ 5,608.7
Unamortized premium/(discounts), net		11.4	(3.2)
Unamortized debt issuance costs		(63.4)	(67.8)
Carrying value of debt		5,543.6	5,537.7
Less current portion		(5)	(5)
Long-term debt, less current portion		5,538.6	5,532.7
6.00% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Debt obligations		$ 1,430	$ 1,430
Interest rate		6.00%	6.00%
6.375% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt obligations		$ 900	$ 900
Interest rate		6.375%	6.375%
5.75% Senior Unsecured Notes due 2027 [Member]
Debt Instrument [Line Items]
Debt obligations		$ 1,650	$ 1,350	$ 300	$ 550	$ 800
Interest rate		5.75%	5.75%
Term Loan Facility
Debt Instrument [Line Items]
Debt obligations							$ 2,500
Carrying value of debt		$ 1,602.6	$ 1,912.7
Term Loan Facility | LIBOR
Debt Instrument [Line Items]
Spread on interest rate	2.75%
Term Loan Facility due 2021 [Member]
Debt Instrument [Line Items]
Debt obligations		$ 496.3	$ 498.8
Term Loan Facility due 2021 [Member] | LIBOR
Debt Instrument [Line Items]
Spread on interest rate		2.00%	2.00%
Term Loan Facility B2 [Member]
Debt Instrument [Line Items]
Debt obligations		$ 1,119.3	$ 1,429.9
Term Loan Facility B2 [Member] | LIBOR
Debt Instrument [Line Items]
Spread on interest rate		2.25%	2.25%

LONG-TERM DEBT (Narrative) (Det

LONG-TERM DEBT (Narrative) (Details) - USD ($) $ in Millions

Dec. 22, 2017

Jul. 20, 2017

Jul. 05, 2017

Apr. 10, 2017

Jan. 27, 2017

Jan. 19, 2017

Jul. 22, 2016

Apr. 14, 2016

May 06, 2015

Jan. 15, 2015

Jul. 31, 2017

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Jun. 30, 2017

Mar. 09, 2015

Jan. 23, 2015

Debt Instrument [Line Items]

Interest rate decrease (basis point)

(1.00%)

Payments of Debt Extinguishment Costs

$ 4.9

Debt obligations

$ 5,595.6

$ 5,595.6

$ 5,608.7

Proceeds from issuance of private placement

$ 310.7

312.8

Repayment of debt

313.2

Loss on extinguishment of debt

$ 4.9

Secured debt ratio

4.50

4.50

Debt issuance costs

$ 113.1

$ 113.1

Accumulated amortization

49.7

49.7

$ 45.1

Interest expense associated with the amortization of debt issuance costs

$ 2.3

$ 2.2

$ 4.7

$ 4.4

Revolver [Member]

Debt Instrument [Line Items]

Outstanding letters of credit increased

$ 50

Letters of Credit [Member]

Debt Instrument [Line Items]

Unused commitment, percentage

0.25%

Secured Debt [Member] | Revolver [Member]

Debt Instrument [Line Items]

Line of credit facility maximum borrowing capacity

$ 450

Weighted average interest rate

3.30%

3.30%

3.80%

Remaining borrowing capacity

$ 442

$ 442

Percentage of excess revolver committed to debt payments

35.00%

Secured debt ratio

5.25

5.25

Secured Debt [Member] | Letters of Credit [Member]

Debt Instrument [Line Items]

Quarterly principal payments per quarter, in basis points

0.25%

Percentage of excess cash flows committed to debt payments

50.00%

Outstanding letters of credit

$ 8

$ 8

Term Loan Facility

Debt Instrument [Line Items]

Interest rate decrease (basis point)

(0.75%)

Weighted average interest rate

3.70%

3.70%

3.40%

Aggregate principal amount outstanding

$ 1,615.6

Debt obligations

$ 2,500

Repriced percentage

99.75%

Repayment of debt

$ 570.1

$ 196

$ 310.7

Incremental Term Loan [Member]

Debt Instrument [Line Items]

Line of credit facility maximum borrowing capacity

$ 400

Priced percent of additional line of credit

99.00%

Debt obligations

$ 1,850

Repriced percentage

99.75%

Incremental Term Loan [Member] | Electric Lightwave

Debt Instrument [Line Items]

Interest rate decrease (basis point)

(0.25%)

Maturity period from incurrence

7 years

Debt obligations

$ 650

Minimum | Revolver [Member]

Debt Instrument [Line Items]

Unused commitment, percentage

0.25%

Maximum

Debt Instrument [Line Items]

Total indebtedness ratio

6

6

Maximum | Revolver [Member]

Debt Instrument [Line Items]

Unused commitment, percentage

0.375%

Tranche One [Member] | Incremental Term Loan [Member]

Debt Instrument [Line Items]

Interest rate decrease (basis point)

(0.75%)

Maturity period from incurrence

4 years

Debt obligations

$ 500

Tranche Two [Member] | Incremental Term Loan [Member]

Debt Instrument [Line Items]

Interest rate decrease (basis point)

(0.25%)

Maturity period from incurrence

7 years

Debt obligations

$ 1,350

6.00% Senior Notes due 2023 [Member]

Debt Instrument [Line Items]

Debt obligations

$ 1,430

$ 1,430

$ 1,430

Interest rate of debt redeemed

6.00%

6.00%

6.00%

6.00% Senior Notes due 2023 [Member] | Unsecured Notes | Zayo Group Ltd (ZGL) [Member]

Debt Instrument [Line Items]

Debt obligations

$ 700

6.00% Senior Notes due 2023 [Member] | Unsecured Notes | Zayo Capital [Member]

Debt Instrument [Line Items]

Debt obligations

$ 730

6.375% New Senior Notes due 2025 [Member] | Unsecured Notes | Zayo Group Ltd (ZGL) and Zayo Capital [Member]

Debt Instrument [Line Items]

Debt obligations

550

6.375% Senior Notes due 2025 [Member]

Debt Instrument [Line Items]

Debt obligations

$ 900

$ 900

$ 900

Interest rate of debt redeemed

6.375%

6.375%

6.375%

6.375% Senior Notes due 2025 [Member] | Unsecured Notes | Zayo Group Ltd (ZGL) and Zayo Capital [Member]

Debt Instrument [Line Items]

Debt obligations

350

5.75% Senior Unsecured Notes due 2027 [Member]

Debt Instrument [Line Items]

Debt obligations

$ 300

$ 550

$ 800

$ 1,650

$ 1,650

$ 1,350

Debt price percentage

104.25%

104.00%

Interest rate of debt redeemed

5.75%

5.75%

5.75%

10.125% Senior Notes due 2020 [Member]

Debt Instrument [Line Items]

Repayment of debt

325.6

Redemption premium and accrued interest included in redemption amount

$ 20.3

Interest rate of debt redeemed

10.125%

LIBOR | Term Loan Facility

Debt Instrument [Line Items]

Spread on interest rate

2.75%

LIBOR | Incremental Term Loan [Member]

Debt Instrument [Line Items]

Spread on interest rate

3.50%

LIBOR | Incremental Term Loan [Member] | Electric Lightwave

Debt Instrument [Line Items]

Spread on interest rate

2.25%

2.50%

LIBOR | Minimum | Letters of Credit [Member]

Debt Instrument [Line Items]

Fee on outstanding letters of credit based upon leverage ratio

1.00%

LIBOR | Minimum | Term Loan Facility

Debt Instrument [Line Items]

Spread on interest rate

1.00%

1.00%

LIBOR | Minimum | Incremental Term Loan [Member]

Debt Instrument [Line Items]

Spread on interest rate

1.00%

LIBOR | Minimum | Incremental Term Loan [Member] | Electric Lightwave

Debt Instrument [Line Items]

Spread on interest rate

1.00%

1.00%

LIBOR | Maximum | Letters of Credit [Member]

Debt Instrument [Line Items]

Fee on outstanding letters of credit based upon leverage ratio

1.75%

LIBOR | Maximum | Term Loan Facility

Debt Instrument [Line Items]

Spread on interest rate

1.75%

LIBOR | Tranche One [Member] | Incremental Term Loan [Member]

Debt Instrument [Line Items]

Spread on interest rate

2.00%

LIBOR | Tranche One [Member] | Minimum | Incremental Term Loan [Member]

Debt Instrument [Line Items]

Spread on interest rate

0.00%

LIBOR | Tranche Two [Member] | Incremental Term Loan [Member]

Debt Instrument [Line Items]

Spread on interest rate

2.50%

LIBOR | Tranche Two [Member] | Minimum | Incremental Term Loan [Member]

Debt Instrument [Line Items]

Spread on interest rate

1.00%

INCOME TAXES (Reconciliation of

INCOME TAXES (Reconciliation of Income Tax Provision) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
INCOME TAXES
Expected provision at the statutory rate	$ 7.6	$ 7.1	$ 17.6	$ 14.8
State income taxes benefit, net of federal benefit	0.9	0.8	1.5	1.5
Stock-based compensation	1	(2.9)	2.5	0.4
Transaction costs not deductible for tax purposes	0.1	0.2	0.2	0.3
Change in statutory tax rate, non-US	0.8		0.8	(1.7)
Foreign tax rate differential	0.5	0.4	(1.7)	(0.3)
Change in valuation allowance	(25.7)	(4.4)	(31.4)	(6.7)
US Tax Reform	44.1		44.1
Other, net	(6.4)	(1)	(5.3)	(1.5)
Provision for income taxes	$ 22.9	$ 0.2	$ 28.3	$ 6.8

INCOME TAXES (Narrative) (Detai

INCOME TAXES (Narrative) (Details) - USD ($) $ in Millions	Dec. 22, 2017	Dec. 21, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Operating Loss Carryforwards [Line Items]
Effective tax rates	21.00%	35.00%					21.00%	28.00%	35.00%
Provision to return adjustment for entities in France			$ (6.4)	$ (1)	$ (5.3)	$ (1.5)
Liability for uncertain tax positions related to state taxing jurisdictions			0.2		0.2
Accrued interest and penalties			0.1		0.1
Deferred tax liablity changes to indefinite reinvestment assertion			$ 7.9		7.9
Canada
Operating Loss Carryforwards [Line Items]
Reverse of valuation allowance on deferred tax assets of certain Canadian subsidiaries					28.5
France
Operating Loss Carryforwards [Line Items]
Provision to return adjustment for entities in France					$ 6.9

INCOME TAXES (U.S. Tax Reform)

INCOME TAXES (U.S. Tax Reform) (Details) $ in Millions	6 Months Ended
	Dec. 31, 2017USD ($)
INCOME TAXES
Tax expenses change in statutory tax rate, U.S. only	$ 1.4
Tax expenses changes to indefinite reinvestment assertion	7.9
Tax expenses Repatriation Tax (settled with NOL, non -cash)	34.8
Tax expenses Net discrete impacts of the enactment of U.S. Tax Reform	44.1
Deferred tax liability change in statutory tax rate, U.S. only	11.4
Deferred tax liability changes to indefinite reinvestment assertion	7.9
Deferred tax liability Repatriation Tax (settled with NOL, non -cash)	34.8
Deferred tax liability Net discrete impacts of the enactment of U.S. Tax Reform	54.1
Current tax receivable change in statutory tax rate, U.S. only	10
Current tax receivable Net discrete impacts of the enactment of U.S. Tax Reform	$ 10

INCOME TAXES (Statutory Tax Rat

INCOME TAXES (Statutory Tax Rate) (Details)	Dec. 22, 2017	Dec. 21, 2017	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
INCOME TAXES
Federal Rate	21.00%	35.00%	21.00%	28.00%	35.00%
Blended Federal & State Rate			26.00%	33.00%	39.00%

EQUITY (Narrative) (Details)

EQUITY (Narrative) (Details) $ in Millions	6 Months Ended
	Dec. 31, 2017USD ($)
EQUITY
Increase in additional paid-in capital associated with stock-based compensation expense	$ 47.2

STOCK-BASED COMPENSATION (Summa

STOCK-BASED COMPENSATION (Summary of Stock-based Compensation Expense Liability and Equity Classified Awards Included in Consolidated Statements of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 23.5	$ 34.5	$ 51.3	$ 66.5
Operating Costs [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	2.3	3.3	5.5	6.6
Selling, General and Administrative Expenses [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	21.2	31.2	45.8	59.9
Part A Restricted Stock Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	19.4	18.8	41.6	40.1
Part B Restricted Stock Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	3.6	9.5	8.7	15.7
Part C Restricted Stock Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 0.5	0.3	$ 1	0.6
CII [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense		$ 5.9		$ 10.1

STOCK-BASED COMPENSATION (Narra

STOCK-BASED COMPENSATION (Narrative) (Details) - USD ($) $ in Millions	Oct. 16, 2014	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense		$ 23.5				$ 34.5		$ 51.3	$ 66.5
Number of RSUs, Granted				152,808	171,316	191,015	200,425
PCIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive plan termination period	10 years									10 days
Part A Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense		19.4				$ 18.8		$ 41.6	40.1
Average closing price								10 days
Unrecognized compensation cost		27.3						$ 27.3
Award recorded as liability		6		$ 5.5				$ 6		$ 5.5
Number of RSUs, Granted								1,158,872
Vesting period			12 months							15 months
Part B Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense		3.6				9.5		$ 8.7	15.7
Unrecognized compensation cost		$ 5.7						$ 5.7
Number of RSUs, Granted		82,556	163,960					246,516
Part C Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense		$ 0.5				$ 0.3		$ 1	$ 0.6
Average closing price								10 days
Number of RSUs, Granted		11,230				14,261		21,841	29,947
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Average closing price								10 days
Performance price								1 year
CII [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based compensation expense						$ 5.9			$ 10.1

STOCK-BASED COMPENSATION (Sum46

STOCK-BASED COMPENSATION (Summary Of Restricted Stock Units Activity) (Details) - $ / shares	3 Months Ended						6 Months Ended	12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2017	Jun. 30, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of RSUs, Granted			152,808	171,316	191,015	200,425
Weighted average grant-date fair value per share, Granted			$ 26.52	$ 27.39	$ 75.56	$ 47
Part A Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of RSUs, Outstanding beginning balance		2,364,386					2,364,386
Number of RSUs, Granted							1,158,872
Number of RSUs, Vested							(1,460,389)
Number of RSUs, Forfeited							(193,105)
Number of RSUs, Outstanding ending balance	1,869,764		2,364,386				1,869,764	2,364,386
Weighted average grant-date fair value per share, Outstanding beginning balance		$ 31.63					$ 31.63
Weighted average grant-date fair value per share, Granted							34.96
Weighted average grant-date fair value per share, vested							31.54
Weighted average grant-date fair value per share, Forfeited							0
Weighted average grant-date fair value per share, Outstanding ending balance	$ 33.42		$ 31.63				$ 33.42	$ 31.63
Weighted average remaining contractual term in months							7 years 4 months 24 days	7 years 1 month 6 days
Part B Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of RSUs, Outstanding beginning balance		411,973					411,973
Number of RSUs, Granted	82,556	163,960					246,516
Number of RSUs, Vested							(252,529)
Number of RSUs, Forfeited							(6,636)
Number of RSUs, Outstanding ending balance	399,324		411,973				399,324	411,973
Weighted average grant-date fair value per share, Outstanding beginning balance		$ 42.86					$ 42.86
Weighted average grant-date fair value per share, Granted	$ 45.10	$ 19.06					27.28
Weighted average grant-date fair value per share, vested							52.49
Weighted average grant-date fair value per share, Forfeited							0
Weighted average grant-date fair value per share, Outstanding ending balance	$ 27.30		$ 42.86				$ 27.30	$ 42.86
Weighted average remaining contractual term in months							6 years	6 years 1 month 6 days

STOCK-BASED COMPENSATION (Sum47

STOCK-BASED COMPENSATION (Summary Of Part B RSUs Granted, Maximum Eligible Shares Of Stock And Grant Date Fair Value Per Part B RSU) (Details) - $ / shares	3 Months Ended						6 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Part B RSUs granted			152,808	171,316	191,015	200,425
Maximum eligible shares of the Company's common stock			550,109	880,564	981,817	1,030,185
Grant date fair value			$ 26.52	$ 27.39	$ 75.56	$ 47
Units converted to Company's common stock at vesting date				41,368	102,511	99,508
Part B Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Part B RSUs granted	82,556	163,960					246,516
Maximum eligible shares of the Company's common stock	569,636	590,256					569,636
Grant date fair value	$ 45.10	$ 19.06					$ 27.28

EMPLOYEE BENEFITS (Changes in B

EMPLOYEE BENEFITS (Changes in Benefit Obligations, Fair Value of Plan Assets and Underfunded Status for Company's Defined Benefit Pension and Postretirement Benefit Plans) (Details) CAD in Millions, $ in Millions	Oct. 31, 2017CAD	Oct. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017USD ($)
Defined Benefit Plan Disclosure [Line Items]
Assets transferred resulting from Allstream acqusition	CAD 117.9	$ 91.6
Amounts reclassified from AOCI				$ 0
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at end of year			$ 97.2	97.2
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Fair value of plan assets			97.2	97.2	$ 97.2
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation					99.2
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year				6.7
Service cost			0.7	1.5
Interest cost			0.6	0.7
Actuarial loss (gain)				(1.3)
Participant contributions				0.3
Benefits paid from plan assets				(3.6)
Acquisition transfer				102.1
Foreign currency exchange rate changes				0.1
Foreign currency exchange rate changes				0.2
Projected benefit obligation at end of year			106.6	106.6
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year				3.7
Return on plan assets				1.2
Employer contributions				1.6
Participant contributions				0.3
Benefits paid from plan assets				(3.6)
Acquisition transfer				93.9
Foreign currency exchange rate changes				0.1
Fair value of plan assets at end of year			97.2	97.2
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Projected benefit obligation			106.6	6.7	106.6
Fair value of plan assets			97.2	3.7	97.2
Unfunded status					(9.4)
Non-current portion of unfunded status					9.4
Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation					10.1
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year				9.9
Service cost				0.1
Interest cost			0.1	0.2
Benefits paid from plan assets				(0.3)
Foreign currency exchange rate changes				0.2
Projected benefit obligation at end of year			10.1	10.1
Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract]
Projected benefit obligation			$ 10.1	$ 9.9	$ 10.1

EMPLOYEE BENEFITS (Amounts in A

EMPLOYEE BENEFITS (Amounts in AOCI not Recognized as Components of Net Periodic Benefit Cost) (Details) $ in Millions	6 Months Ended
	Dec. 31, 2017USD ($)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Total plans, at the beginning of period	$ (0.8)
Total plans - Deferrals	(5)
Total plans - Net Change in AOCL	(5)
Total plans, at the end of period	(5.8)
Post-Retirement Benefit Plans [Member]
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net actuarial (loss) gain, at the beginning of period	(1.2)
Deferred income tax benefit (expense), at the beginning of period	(0.4)
Total plans, at the beginning of period	(0.8)
Net actuarial (loss) gain, at the end of period	(1.2)
Deferred income tax benefit (expense), at the end of period	0.4
Total plans, at the end of period	(0.8)
Pension Plans [Member]
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax [Abstract]
Net actuarial (loss) gain - Deferrals	1.3
Prior service benefit (cost) - Deferrals	(8)
Deferred income tax benefit (expense) - Deferrals	1.7
Total plans - Deferrals	(5)
Net actuarial (loss) gain - Net Change in AOCL	1.3
Prior service benefit (cost) - Net Change in AOCL	(8)
Deferred income tax benefit (expense) - Net Change in AOCL	1.7
Total plans - Net Change in AOCL	5
Net actuarial (loss) gain, at the end of period	1.3
Prior service benefit (cost), at the end of period	(8)
Deferred income tax benefit (expense), at the end of period	1.7
Total plans, at the end of period	$ (5)

EMPLOYEE BENEFITS (Expected Pay

EMPLOYEE BENEFITS (Expected Payments for Company's Defined Benefit Pension and Postretirement Plans) (Details) $ in Millions	Dec. 31, 2017USD ($)
Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
2,018	$ 0.6
2,019	0.6
2,020	0.6
2,021	0.5
2,022	0.5
2023-2027	2.5
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
2,018	2.8
2,019	3
2,020	3.2
2,021	3.5
2,022	3.7
2023-2027	$ 22.6

EMPLOYEE BENEFITS (Net Periodic

EMPLOYEE BENEFITS (Net Periodic Pension Benefit Income) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Dec. 31, 2017	Dec. 31, 2017
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0.7	$ 1.5
Interest cost	0.6	0.7
Expected return on plan assets	(1)	(1.1)
Net periodic pension benefit income	0.3	1.1
Post-Retirement Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		0.1
Interest cost	0.1	0.2
Net periodic pension benefit income	$ 0.1	$ 0.3

EMPLOYEE BENEFITS (Assumptions

EMPLOYEE BENEFITS (Assumptions used) (Details)	6 Months Ended
	Dec. 31, 2017
Post-Retirement Benefit Plans [Member]
Actuarial assumptions at date of acquisition:
Discount rate	3.50%
Pension Plans [Member]
Actuarial assumptions at date of acquisition:
Discount rate	3.50%
Price inflation	1.75
Expected long-term rate of return on plan assets	5.90%
Rate of compensation increase	2.00%

EMPLOYEE BENEFITS (Allocation o

EMPLOYEE BENEFITS (Allocation of invested defined benefit pension plan assets) (Details)	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Percentage of defined benefit pension plan assets	100.00%
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Percentage of defined benefit pension plan assets	40.00%
Equities
Defined Benefit Plan Disclosure [Line Items]
Percentage of defined benefit pension plan assets	55.00%
Other
Defined Benefit Plan Disclosure [Line Items]
Percentage of defined benefit pension plan assets	5.00%

EMPLOYEE BENEFITS (Fair value o

EMPLOYEE BENEFITS (Fair value of plan assets valued at NAV) (Details) $ in Millions	Dec. 31, 2017USD ($)
Defined Benefit Plan Disclosure [Line Items]
Amount of defined benefit pension plan assets	$ 97.2
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Amount of defined benefit pension plan assets	36.3
Equities
Defined Benefit Plan Disclosure [Line Items]
Amount of defined benefit pension plan assets	55.9
Other
Defined Benefit Plan Disclosure [Line Items]
Amount of defined benefit pension plan assets	$ 5

FAIR VALUE MEASUREMENTS (Narrat

FAIR VALUE MEASUREMENTS (Narrative) (Details) - USD ($) $ in Millions	Dec. 22, 2017	Jul. 22, 2016	Dec. 31, 2017	Jun. 30, 2017
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value of the notes			$ 5,543.6	$ 5,537.7
Hypothetical annual interest expense			16.2
Term Loan Facility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value of the notes			1,602.6	1,912.7
Term Loan Facility | LIBOR
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Spread on interest rate		2.75%
Term Loan Facility | LIBOR | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Spread on interest rate	1.00%	1.00%
Tranche One [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Debt instrument, face amount			$ 500
Tranche One [Member] | LIBOR
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Spread on interest rate			2.00%
Floor rate			0.00%
Tranche Two [Member] | LIBOR
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Spread on interest rate			2.25%
Floor rate			1.00%
Notes [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value of the notes			$ 4,004.4	3,692.8
Fair value of the notes			$ 4,108.4	3,895.7
Notes [Member] | LIBOR | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Spread on interest rate			1.00%
Notes [Member] | Term Loan Facility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of the notes			$ 1,622.4	1,930.5
Revolver [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value of the notes			$ 0	$ 0

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Narrative) (Details) - Dec. 31, 2017 CAD in Millions, $ in Millions	CAD	USD ($)
Commitment And Contingencies [Line Items]
Purchase commitments		$ 408.4
Outstanding letters of credit		8
Credit Letter Agreement [Member]
Commitment And Contingencies [Line Items]
Outstanding letters of credit	CAD 5	4
Credit letter agreement limit	CAD 3.5	$ 2.8

RELATED PARTY TRANSACTIONS (Sch

RELATED PARTY TRANSACTIONS (Schedule of Revenue and Expense Transactions) (Details) - OVS [Member] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Revenues	$ 1.8	$ 1.5	$ 3.7	$ 3.1
Operating costs	$ 0.6	$ 0.1	$ 1.2	$ 0.2

RELATED PARTY TRANSACTIONS (Nar

RELATED PARTY TRANSACTIONS (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2017
Inteliquent, Inc [Member]
Related Party Transaction [Line Items]
Due from related parties	$ 0.6		$ 0.6		$ 0.5
Dan Caruso [Member] | Aircraft Reimbursement [Member]
Related Party Transaction [Line Items]
Payable to related party settled	$ 0.2	$ 0.2	$ 0.3	$ 0.4

SEGMENT REPORTING (Narrative) (

SEGMENT REPORTING (Narrative) (Details)	6 Months Ended
	Dec. 31, 2017segmentitem
Segment Reporting Information [Line Items]
Number of segments | segment	6
Fiber Solutions [Member] | Minimum
Segment Reporting Information [Line Items]
Number of dark fiber pairs leased to customers	2
Contract term	3 years
Fiber Solutions [Member] | Maximum
Segment Reporting Information [Line Items]
Number of dark fiber pairs leased to customers	12
Contract term	20 years
Transport [Member] | Minimum
Segment Reporting Information [Line Items]
Contract term	2 years
Transport [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	5 years
Enterprise Networks [Member] | Minimum
Segment Reporting Information [Line Items]
Contract term	1 year
Enterprise Networks [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	10 years
zColo [Member] | Minimum
Segment Reporting Information [Line Items]
Contract term	2 years
zColo [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	5 years
Other [Member]
Segment Reporting Information [Line Items]
Contract term	1 year

SEGMENT REPORTING (Summary of F

SEGMENT REPORTING (Summary of Financial Information by Segments) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2017
Segment Reporting Information [Line Items]
Revenue from external customers	$ 653.5	$ 506.7	$ 1,297	$ 1,011.6
Segment Adjusted EBITDA	329.9	263.4	646.5	524
Total assets	8,935.9		8,935.9		$ 8,739.4
Capital expenditures	193.4	213.6	386.8	421.9
Fiber Solutions [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	200.5	177.5	396	351.6
Segment Adjusted EBITDA	161	141	315.2	279.2
Total assets	4,701.7		4,701.7		4,504.6
Capital expenditures	114.5	130.9	221.8	261.7
Transport [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	117.3	106.4	236.4	212.5
Segment Adjusted EBITDA	49.2	44.6	100.8	89.2
Total assets	1,257.6		1,257.6		1,230
Capital expenditures	31.8	37.4	65.5	70.9
Enterprise Networks [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	145.9	114.7	283.6	229.1
Segment Adjusted EBITDA	57	39.7	106.5	80.3
Total assets	1,293.2		1,293.2		1,385.7
Capital expenditures	19.5	20.1	40.5	41
zColo [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	59.9	52.5	118.3	103.7
Segment Adjusted EBITDA	31.5	27.6	60.9	53.9
Total assets	1,007.1		1,007.1		994.4
Capital expenditures	24.7	23.3	52.6	46.2
Allstream
Segment Reporting Information [Line Items]
Revenue from external customers	123.5	51.6	251.2	106.1
Segment Adjusted EBITDA	29.9	9.6	60.7	19.3
Total assets	487.1		487.1		406.2
Capital expenditures	2.9	1.9	6.4	2.1
Other [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	6.4	4	11.5	8.6
Segment Adjusted EBITDA	1.3	$ 0.9	2.4	$ 2.1
Total assets	32.3		32.3		33.2
Corp/Eliminations [Member]
Segment Reporting Information [Line Items]
Total assets	$ 156.9		$ 156.9		$ 185.3

SEGMENT REPORTING (Reconciliati

SEGMENT REPORTING (Reconciliation from Segment Adjusted EBITDA to Net Loss from Continuing Operations) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
SEGMENT REPORTING
Total Segment Adjusted EBITDA	$ 329.9	$ 263.4	$ 646.5	$ 524
Interest expense	(73.1)	(53.7)	(146.7)	(107)
Depreciation and amortization expense	(195.9)	(131.4)	(380)	(269.9)
Transaction costs	(5.9)	(6.2)	(14.2)	(9.2)
Stock-based compensation	(23.5)	(34.5)	(51.3)	(66.5)
Loss on extinguishment of debt			(4.9)
Foreign currency gain/(loss) on intercompany loans	3.1	(17.4)	13.9	(28.6)
Non-cash loss on investments	(0.2)	(0.2)	(0.3)	(0.5)
Income from operations before income taxes	$ 34.4	$ 20	$ 63	$ 42.3

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Subsequent Event [Member] CAD in Millions, $ in Millions	Jan. 28, 2018USD ($)mi	Jan. 18, 2018CADitemmi	Jan. 18, 2018USD ($)itemmi
Optic Zoo Networks [Member]
Subsequent Event [Line Items]
Cash acquisition		CAD 31	$ 24.9
Acquired route miles added to fiber network		103	103
Optic Zoo Networks [Member] | Minimum
Subsequent Event [Line Items]
Number of on-net buildings connected | item		100	100
Neutral Path Communications And Near North Partners [Member]
Subsequent Event [Line Items]
Cash acquisition | $	$ 31.5
Acquired route miles added to fiber network	452