Zayo 10-Q 9 Feb 17 2017 Q2 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	6 Months Ended
	Dec. 31, 2016	Feb. 07, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,017
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		244,115,095

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Dec. 31, 2016	Jun. 30, 2016
Current assets
Cash and cash equivalents	$ 144	$ 170.7
Trade receivables, net of allowance of $8.0 and $7.5 as of September 30, 2016 and June 30, 2016, respectively	156.7	148.4
Prepaid expenses	52.9	68.8
Other assets	8.6	9.2
Total current assets	362.2	397.1
Property and equipment, net	4,286.5	4,079.5
Intangible assets, net	902.7	934.9
Goodwill	1,196.9	1,214.5
Deferred income taxes, net	7	7
Other assets	112.4	94.5
Total assets	6,867.7	6,727.5
Current liabilities
Accounts payable	39.9	97
Accrued liabilities	260	225.7
Accrued interest	28.8	28.6
Capital lease obligations, current	7.8	5.8
Deferred revenue, current	121.1	129.4
Total current liabilities	457.6	486.5
Long-term debt, non-current	4,091.3	4,085.3
Capital lease obligation, non-current	76.6	44.9
Deferred revenue, non-current	849.4	793.3
Deferred income taxes, net	39.2	41.3
Other long-term liabilities	66.1	57
Total liabilities	5,580.2	5,508.3
Commitments and contingencies (Note 10)
Stockholders' equity
Common stock, $0.001 par value - 850,000,000 shares authorized; 244,115,095 and 242,649,498 shares issued and outstanding as of December 31, 2016 and June 30, 2016, respectively	0.2	0.2
Additional paid-in capital	1,839.5	1,777.6
Accumulated other comprehensive income	(22.9)	4.5
Accumulated deficit	(529.3)	(563.1)
Total stockholders' equity	1,287.5	1,219.2
Total liabilities and stockholders' equity	$ 6,867.7	$ 6,727.5

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2016	Jun. 30, 2016
Statement Of Financial Position [Abstract]
Trade receivables allowance	$ 8.6	$ 7.5
Preferred Stock, par value	$ 0.001	$ 0.001
Preferred Stock, shares authorized	50,000,000	50,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	850,000,000	850,000,000
Common stock, shares issued	244,115,095	242,649,498
Common stock, shares outstanding	244,115,095	242,649,498

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Revenue	$ 506.7	$ 369.6	$ 1,011.6	$ 736.4
Operating costs and expenses
Operating costs (excluding depreciation and amortization and including stock-based compensation—Note 8)	179.9	112.2	353.7	225.2
Selling, general and administrative expenses (including stock-based compensation—Note 8)	104.7	85	210.3	169.6
Depreciation and amortization	131.4	113.7	269.9	230.8
Total operating costs and expenses	416	310.9	833.9	625.6
Operating income	90.7	58.7	177.7	110.8
Other expenses
Interest expense	(53.7)	(51.2)	(107)	(105)
Foreign currency loss on intercompany loans	(17.4)	(7.1)	(28.6)	(17.8)
Other expense, net	0.4	(0.1)	0.2	(0.2)
Total other expenses, net	(70.7)	(58.4)	(135.4)	(123)
Income/(loss) from operations before income taxes	20	0.3	42.3	(12.2)
Provision for income taxes	0.2	11.1	6.8	13.8
Net income/(loss)	$ 19.8	$ (10.8)	$ 35.5	$ (26)
Weighted-average shares used to compute net income/(loss) per share:
Basic	243.1	244.8	242.9	243.9
Diluted	245.6	244.8	244.9	243.9
Net income/(loss) per share:
Basic	$ 0.08	$ (0.04)	$ 0.15	$ (0.11)
Diluted	$ 0.08	$ (0.04)	$ 0.14	$ (0.11)

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Comprehensive Income Net Of Tax [Abstract]
Net income/(loss)	$ 19.8	$ (10.8)	$ 35.5	$ (26)
Foreign currency translation adjustment	(24.1)	(7.7)	(26.2)	(11.7)
Defined benefit pension plan adjustments			(1.2)
Comprehensive income/(loss)	$ (4.3)	$ (18.5)	$ 8.1	$ (37.7)

CONSOLIDATED STATEMENT OF STOCK

CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - 6 months ended Dec. 31, 2016 - USD ($) $ in Millions	Common Stock	Additional paid-in Capital	Accumulated Other Comprehensive (Loss)/Income	Accumulated Deficit	Total
Balance at Jun. 30, 2016	$ 0.2	$ 1,777.6	$ 4.5	$ (563.1)	$ 1,219.2
Balance (in shares) at Jun. 30, 2016	242,649,498				242,649,498
Stock-based compensation		60.2			$ 60.2
Stock-based compensation, shares	1,465,597
Cumulative effect adjustment resulting from adoption of ASU 2016-09 (Note 1)		1.7		(1.7)
Foreign currency translation adjustment			(26.2)		(26.2)
Defined benefit pension plan adjustments			(1.2)		(1.2)
Net income				35.5	35.5
Balance at Dec. 31, 2016	$ 0.2	$ 1,839.5	$ (22.9)	$ (529.3)	$ 1,287.5
Balance (in shares) at Dec. 31, 2016	244,115,095				244,115,095

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS € in Millions, CAD in Millions, $ in Millions	6 Months Ended
	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Cash flows from operating activities
Net income/(loss)	$ 35.5	$ (26)
Adjustments to reconcile net income/(loss) to net cash provided by operating activities
Depreciation and amortization	269.9	230.8
Non-cash interest expense	5.1	6.6
Stock-based compensation	66.5	89
Amortization of deferred revenue	(55.6)	(41.9)
Additions to deferred revenue	84.3	86.6
Foreign currency loss on intercompany loans	28.6	17.8
Excess tax benefit from stock-based compensation		(7.9)
Deferred income taxes	(0.5)	8.3
Provision for bad debts	1.4	2.5
Non-cash loss on investments	0.5	0.6
Changes in operating assets and liabilities, net of acquisitions
Trade receivables	(16.5)	15.3
Accounts payable and accrued liabilities	(33)	(26)
Other assets and liabilities	16.3	(14.3)
Net cash provided by operating activities	402.5	341.4
Cash flows from investing activities
Purchases of property and equipment	(421.9)	(331.6)
Cash paid for acquisitions, net of cash acquired	(1.3)	(117.7)
Other	1.5	(0.3)
Net cash used in investing activities	(421.7)	(449.6)
Cash flows from financing activities
Principal payments on long-term debt		(8.3)
Principal payments on capital lease obligations	(2)	(2.2)
Payment of debt issuance costs	(0.7)
Common stock repurchases		(17.9)
Excess tax benefit from stock-based compensation		7.9
Other		(0.4)
Net cash (used in)/provided by financing activities	(2.7)	(20.9)
Net cash flows	(21.9)	(129.1)
Effect of changes in foreign exchange rates on cash	(4.8)	(3.3)
Net increase in cash and cash equivalents	(26.7)	(132.4)
Cash and cash equivalents, beginning of year	170.7	308.6
Cash and cash equivalents, end of period	144	176.2
Supplemental disclosure of non-cash investing and financing activities:
Cash paid for interest, net of capitalized interest	97.3	112.5
Cash paid for income taxes	6	6.7
Non-cash purchases of equipment through capital leasing	37.9	5.8
Increase in accounts payable and accrued expenses for purchases of property and equipment - continuing operations	$ 22.7	$ 25.5

Business and Basis of Presentat

Business and Basis of Presentation	6 Months Ended
	Dec. 31, 2016
Business and Basis of Presentation [Abstract]
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 bandwidth infrastructure services. 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 operates bandwidth infrastructure assets, including fiber networks and data centers, in the United States, Canada and Europe to offer: · Dark Fiber Solutions, including dark fiber and mobile infrastructure services. · Colocation and Cloud Infrastructure, including cloud and colocation services. · Network Connectivity, wavelengths, Ethernet, IP and SONET services. · Other services, including Zayo Professional Services (“ZPS”), voice and unified communications. 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 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 consolidated financial statements should, therefore, be read in conjunction with the consolidated financial statements and notes thereto for the year ended June 30, 2016 included in the Company’s Annual Report on Form 10-K for the year ended June 30, 2016. 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. Certain amounts in the prior period financial statements have been condensed to conform to the current period presentation and had no impact on reported net income or losses. The results of operations for the three and six months ended December 31, 2016 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 ended June 30, 2016 as “Fiscal 2016” and the fiscal year ending June 30, 2017 as “Fiscal 2017.” Earnings or Loss per Share Basic earnings or loss per share attributable to the Company’s common shareholders is computed by dividing net earnings or loss attributable to common shareholders by the weighted average number of common shares outstanding for the period. Diluted earnings or loss 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. No such items were included in the computation of diluted loss per share for the three and six months ended December 31, 2015 as the Company incurred a loss from operations in that period and the effect of inclusion would have been anti-dilutive. The effect of 2.1 million and 2.0 million incremental shares attributable to the release of Part A and Part B units upon vesting (treasury method) were included in the computation of diluted income per share for the three and six months ended December 31, 2016, respectively. Significant Accounting Policies Upon early adoption of ASU 2016-09 (as described below), the Company elected to change its accounting policy to account for forfeitures as they occur versus estimating forfeitures. The Company recognizes all stock-based awards to employees and independent directors based on their grant-date fair values, with no consideration for future forfeitures. The Company recognizes the fair value of outstanding awards as a charge to operations over the vesting period. 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, 2016. 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 and estimating the 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 January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business.” The new standard provides guidance for evaluating whether transactions should be accounted for as acquisitions of assets or businesses. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted for transactions for which the acquisition date occurs before the issuance date or effective date, only when the transaction has not been reported in financial statements that have been issued or made available for issuance. The Company has elected to early adopt the standard as of January 1, 2017 and will apply the provisions of this standard for acquistions consummated subsequent to that date. 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 , 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. Early adoption is permitted. The new 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 is evaluating the effect that ASU 2016-02 will have on its consolidated financial statements and related disclosures. The Company has not yet selected a transition method nor has it determined the effect of the standard on its ongoing financial reporting. On March 30, 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , which is intended to improve the accounting for share-based payment transactions as part of the FASB’s simplification initiative. The ASU changes five aspects of the accounting for share-based payment award transactions that will affect public companies, including: (1) accounting for income taxes; (2) classification of excess tax benefits on the statement of cash flows; (3) forfeitures; (4) minimum statutory tax withholding requirements; and (5) classification of employee taxes paid on the statement of cash flows when an employer withholds shares for tax-withholding purposes. The Company early-adopted ASU 2016-09 effective July 1, 2016. Excess tax benefits for share-based payments are now recognized against income tax expense rather than additional paid-in capital and are included in operating cash flows rather than financing cash flows. The recognition of excess tax benefits have been applied prospectively and prior periods have not been adjusted. The Company had $4.3 million of excess tax benefits for the six months ended December 31, 2016. In addition, the Company elected to change its accounting policy to account for forfeitures as they occur. The change was applied on a modified retrospective basis with a cumulative effect adjustment to accumulated deficit of $1.7 million as of July 1, 2016. Amendments related to minimum statutory tax withholding requirements and the classification of employee taxes paid on the statement of cash flows when an employer withholds shares for tax-withholding purposes have been adopted prospectively and did not have a material impact on the condensed consolidated financial statements. 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 in 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. Early adoption is 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. The Company is evaluating the effect that ASU 2014-09 will have on the Company and its consolidated financial statements and related disclosures. The Company has not yet selected a transition method nor has it determined the effect of the standard on its ongoing financial reporting.

Acquisitions

Acquisitions	6 Months Ended
	Dec. 31, 2016
Acquisitions [Abstract]
Acquisitions	(2) ACQUISITIONS Since inception, the Company has consummated 39 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 Completed During Fiscal 2017 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 $12.8 million. The net purchase consideration, which was valued using a discounted flow method, will be made in ten quarterly payments of $1.3 million beginning in the December 2016 quarter. As of December 31, 2016, the remaining cash consideration to be paid was $11.5 million. The acquisition was considered an asset purchase for tax purposes. The Santa Clara Data Center, located at 5101 Lafayette Street, includes 26,900 total square feet and three megawatts (MW) of critical 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. Acquisitions Completed During Fiscal 2016 Clearview On April 1, 2016, the Company acquired 100% of the equity interest in Clearview International, LLC (“Clearview”), a Texas based colocation and cloud infrastructure services provider for cash consideration of $18.3 million, subject to certain post-closing adjustments. $1. 1 million of the purchase consideration is currently held in escrow pending the expiration of the indemnification adjustment period. The acquisition was funded with cash on hand and was considered an asset purchase for tax purposes. The acquisition consisted of two Texas data centers. The data centers, located at 6606 LBJ Freeway in Dallas, Texas and 700 Austin Avenue in Waco, Texas, added approximately 30,000 square feet of colocation space, as well as a set of hybrid cloud infrastructure services that complement the Company’s global cloud capabilities. Allstream On January 15, 2016, the Company acquired 100% of the equity interest in Allstream, Inc. and Allstream Fiber U.S. Inc. (together “Allstream”) from Manitoba Telecom Services Inc. (“MTS”) for cash consideration of CAD $422.9 million (or $297.6 million), net of cash acquired, subject to certain post-closing adjustments. The consideration paid is net of $29.6 million of working capital and other liabilities assumed by the Company in the acquisition. The acquisition was funded with Term Loan Proceeds (as defined in Note 5 – Long-Term Debt ). The acquisition was considered a stock purchase for tax purposes. The acquisition added more than 18,000 route miles to the Company’s fiber network, including 12,500 miles of long-haul fiber connecting all major Canadian markets and 5,500 route miles of metro fiber network connecting approximately 3,300 on-net buildings concentrated in Canada’s top five metropolitan markets. As part of the Allstream acquisition, MTS agreed to retain Allstream’s former defined benefit pension obligations, and related pension plan assets, of retirees and other former employees of Allstream and also agreed to reimburse Allstream for certain solvency funding payments related to the pension obligations of active Allstream employees as of January 15, 2016. MTS will transfer assets from Allstream’s former defined benefit pension plans related to pre-closing service obligations for active employees to new Allstream defined benefit pension plans created by the Company, subject to regulatory approval. In addition, if the pre-closing benefit obligation for the January 15, 2016 active employees exceeds the fair value of assets transferred to the new Allstream pension plans, MTS agreed to fund the funding deficiency at the later of the asset transfer date or the date at which it is determined that no further solvency deficit exists. Any required funding of the pension benefit obligation subsequent to January 15, 2016, will be the responsibility of the Company. The amount of the funding deficiency was not material to the financial statements as of December 31, 2016. Also as part of the Allstream acquisition, the Company assumed the liabilities related to Allstream’s other non-pension unfunded post-retirement benefits plans. The liability assumed on January 15, 2016 was approximately $8.3 million. The balance of this liability as of December 31, 2016 was approximately $12.9 million. This liability is currently included in “Other long-term liabilities” on the consolidated balance sheet. Viatel On December 31, 2015, the Company completed the acquisition of a 100% interest in Viatel Infrastructure Europe Ltd., Viatel (UK) Limited, Viatel France SAS, Viatel Deutschland GmbH and Viatel Nederland BV (collectively, “Viatel”) for cash consideration of €92.9 million (or $101.2 million), net of cash acquired. The acquisition was funded with cash on hand. The acquisition was considered a stock purchase for tax purposes. During the six months ended December 31, 2016, the Company received a refund of the purchase price from escrow of $1.5 million. The refund is reflected as a cash inflow from investing activities on the condensed consolidated statement of cash flows for the six months ended December 31, 2016 within the Other caption. Dallas Data Center Acquisition (“Dallas Data Center”) On December 31, 2015, the Company acquired a 36,000 square foot data center located in Dallas, Texas for cash consideration of $16.6 million. The acquisition was funded with cash on hand and was considered an asset purchase for tax purposes. 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. As of December 31, 2016, 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, deferred revenue and resulting deferred taxes related to its acquisitions of Clearview and the Santa Clara Data Center. 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: Santa Clara Data Acquisition date October 3, 2016 (in millions) Property and equipment $ Intangibles Total assets acquired Capital lease obligations Total liabilities assumed Total purchase consideration $ The table below reflects the Company's estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2016 acquisitions: Clearview Allstream Viatel Dallas Data Acquisition date April 1, 2016 January 15, 2016 December 31, 2015 December 31, 2015 (in millions) Cash $ — $ $ $ — Other current assets — Property and equipment Deferred tax assets, net — — Intangibles — Goodwill — — Other assets — Total assets acquired Current liabilities — Deferred revenue — Deferred tax liability, net — — — Other liabilities — Total liabilities assumed — Net assets acquired Less cash acquired — — Net consideration paid $ $ $ $ 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. Note 3 - Goodwill , displays 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 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 on the date of acquisition or disposal, and other direct expenses incurred that are associated with such acquisitions or disposals. The Company incurred transaction costs of $6.2 million and $9.2 million for the three and six months ended December 31, 2016, respectively, and $3.3 million for the three and six months ended December 31, 2015. 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. Pro-forma Financial Information The pro forma results presented below include the effects of the Company’s Fiscal 2017 and 2016 acquisitions as if the acquisitions occurred on July 1, 2015. The pro forma net loss for the periods ended December 31, 2017 and 2016 includes the additional depreciation and amortization resulting from the adjustments to the value of property and equipment and intangible assets resulting from purchase accounting and adjustment to amortized revenue during Fiscal 2017 and 2016 as a result of the acquisition date valuation of assumed deferred revenue. The pro forma results also include interest expense associated with debt used to fund the acquisitions. The pro forma results do not include any anticipated synergies or other expected benefits of the acquisitions. The unaudited pro forma financial information is not necessarily indicative of either future results of operations or results that might have been achieved had the acquisitions been consummated as of July 1, 2015. Three Months Ended December 31, Six Months Ended December 31, 2016 2015 2016 2015 (in millions) Revenue $ $ $ $ Net income/(loss) $ $ $ $

Goodwill

Goodwill	6 Months Ended
	Dec. 31, 2016
Goodwill [Abstract]
Goodwill	(3) GOODWILL The Company’s goodwill balance was $1,196.9 million and $1,214.5 million as of December 31, 2016 and June 30, 2016, respectively. The Company’s reporting units are comprised of its strategic product groups (“SPGs”): Zayo Dark Fiber (“Dark Fiber”), Zayo Wavelength Services (“Waves”), Zayo SONET Services (“SONET”), Zayo Ethernet Services (“Ethernet”), Zayo IP Services (“IP”), Zayo Mobile Infrastructure Group (“MIG”), Zayo Colocation (“zColo"), Zayo Cloud Services (“Cloud”), Allstream business (“Zayo Canada”) and Other (primarily ZPS). The following reflects the changes in the carrying amount of goodwill during the six months ended December 31, 2016: Product Group As of June 30, 2016 Adjustments to Fiscal 2016 Acquisitions Foreign Currency As of December 31, 2016 (in millions) Dark Fiber $ $ $ $ Waves Sonet — Ethernet IP — MIG — — zColo Cloud — Other — Total $ $ $ $

Intangible Assets

Intangible Assets	6 Months Ended
	Dec. 31, 2016
Intangible Assets [Abstract]
Intangible Assets	(4) INTANGIBLE ASSETS Identifiable intangible assets as of December 31, 2016 and June 30, 2016 were as follows: Gross Carrying Amount Accumulated Net (in millions) December 31, 2016 Finite-Lived Intangible Assets Customer relationships $ $ $ Underlying rights Total Indefinite-Lived Intangible Assets Certifications — Underlying Rights — Total $ $ $ June 30, 2016 Finite-Lived Intangible Assets Customer relationships $ $ $ Trade names — Underlying rights Total Indefinite-Lived Intangible Assets Certifications — Underlying Rights — Total $ $ $

Long-Term Debt

Long-Term Debt	6 Months Ended
	Dec. 31, 2016
Long-Term Debt [Abstract]
Long-Term Debt	(5) LONG-TERM DEBT As of December 31, 2016 and June 30, 2016, long-term debt was as follows: December 31, June 30, 2016 2016 (in millions) Term Loan Facility due 2021 $ $ 6.00% Senior Unsecured Notes due 2023 6.375% Senior Unsecured Notes due 2025 Total debt obligations Unamortized discount on Term Loan Facility Unamortized premium on 6.00% Senior Unsecured Notes due 2023 Unamortized discount on 6.375% Senior Unsecured Notes due 2025 Unamortized debt issuance costs Carrying value of debt $ $ Term Loan Facility due 2021 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 the outstanding term loans under the Term Loan Facility to May 6, 2021. The interest rate margins applicable to the Term Loan Facility were decreased by 25 basis points to LIBOR plus 2.75% with a minimum LIBOR of 1.0%. In addition, the amended and restated Credit Agreement removed the fixed charge coverage ratio covenant and replaced such covenant with a springing senior secured leverage ratio maintenance requirement applicable only to the Revolver, increased certain lien and debt baskets, and removed certain covenants related to collateral. The terms of the Term Loan Facility require the Company to make quarterly principal payments of $5.1 million plus an annual payment of up to 50% of excess cash flow, as determined in accordance with the Credit Agreement (no such payment was required during the three or six months ended December 31, 2016 or 2015). The Revolver matures at the earliest of (i) April 17, 2020 and (ii) six months prior to the maturity date of the Term Loan Facility, subject to amendment thereof. 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 accrue interest at a rate ranging from LIBOR plus 2.0% to LIBOR plus 3.0% per annum based upon ZGL’s leverage ratio. 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 Term Loan Facility 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% (the “Term Loan Proceeds”). The issue discount of $4.8 million on the Amendment is being accreted to interest expense over the term of the Term Loan Facility under the effective interest method. No other terms of the Credit Agreement were amended. The Term Loan Proceeds were used to fund the Allstream acquisition (see Note 2 – Acquisitions ) 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 Amendment, the Incremental Term Loan was repriced to 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. The weighted average interest rates (including margins) on the Term Loan Facility were approximately 3.75% and 3.9% at December 31, 2016 and June 30, 2016, respectively. Interest rates on the Revolver as of December 31, 2016 and June 30, 2016 were approximately 3.8% and 3.4%, respectively. As of December 31, 2016, no amounts were outstanding under the Revolver. Standby letters of credit were outstanding in the amount of $7.3 million as of December 31, 2016, leaving $442.7 million available under the Revolver. 6.00% Senior Unsecured Notes Due 2023 and 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 additional 2025 Unsecured Notes (the “New 2025 Notes”). The New 2025 Notes were an additional issuance of the existing 6.375% senior unsecured notes due in 2025 (the “2025 Unsecured Notes”) and were priced at 97.1%. The issue discount of $15.9 million of the New 2025 Notes is being accreted to interest expense over the term of the New 2025 Notes using the effective interest method. The net proceeds from the offering plus cash on hand (i) were used to 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) were used to repay $196.0 million of borrowings under its secured Term Loan Facility. Per the terms of the Credit Agreement, the $196.0 million prepayment on the Term Loan Facility relieves the Company of its obligation to make quarterly principal payments on the Term Loan Facility until the cumulative amount of such relieved payments exceeds $196.0 million. The Company recorded a $2.1 million loss on extinguishment of debt associated with the write-off of unamortized debt discount on the Term Loan Facility accounted for as an extinguishment during the fourth quarter of Fiscal 2016. Following the offering of the New 2025 Notes, $900.0 million aggregate principal amount of the 2025 Unsecured Notes is outstanding. Debt covenants The indentures (the “Indentures”) governing the 6.00% senior unsecured notes due 2023 (the “2023 Unsecured Notes”) and the 2025 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 such 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, 2016. 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. 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 $90.1 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. Unamortized debt issuance costs of $11.4 million associated with the Company’s previous indebtedness were recorded as part of the loss on extinguishment of debt during the fourth quarter of Fiscal 2016. The balance of debt issuance costs as of December 31, 2016 and June 30, 2016 was $49.9 million and $53.8 million, net of accumulated amortization of $40.2 million and $35.8 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 and changes in the fair value of the Company’s interest rate derivatives. Interest expense associated with the amortization of debt issuance costs was $2.2 million and $4.4 million for the three and six months ended December 31, 2016, respectively, and $2.5 million and $5.0 million for the three and six months ended December 31, 2015, respectively. Debt issuance costs are presented in the condensed consolidated balance sheets as a reduction to “Long-term debt, non-current”. Interest rate derivatives On August 13, 2012, the Company entered into forward-starting interest rate swap agreements with an aggregate notional value of $750.0 million, a maturity date of June 30, 2017, and a start date of June 30, 2013. There were no up-front fees for these agreements. The contract states that the Company shall pay a 1.67% fixed rate of interest for the term of the agreement beginning on the start date. The counter-party will pay to the Company the greater of actual LIBOR or 1.25%. The Company entered in to the forward-starting swap arrangements to reduce the risk of increased interest costs associated with potential changes in LIBOR rates. Changes in the fair value of interest rate swaps are recorded in interest expense in the condensed consolidated statements of operations for the applicable period. The fair value of the interest rate swaps of $1.5 million and $3.0 million are included in “Other long term liabilities” in the Company’s condensed consolidated balance sheets as of December 31, 2016 and June 30, 2016, respectively. During the three and six months ended December 31, 2016, $0.8 million and $1.5 million, respectively, was recorded as a decrease in interest expense for the change in fair value of the interest rate swaps. During the three and six months ended December 31, 2015, $1.0 million and $0.6 million, respectively, was recorded as a decrease in interest expense for the change in fair value of the interest rate swaps.

Income Taxes

Income Taxes	6 Months Ended
	Dec. 31, 2016
Income Taxes [Abstract]
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, 2016 and 2015 is as follows: Three months ended December 31, Six months ended December 31, 2016 2015 2016 2015 (in millions) Expected expense/(benefit) at the statutory rate $ $ $ $ Increase/(decrease) due to: Non-deductible stock-based compensation Excess tax benefit on stock-based compensation — — State income taxes benefit, net of federal benefit Transactions costs not deductible for tax purposes Change in tax rates — — — Foreign tax rate differential Foreign entities with valuation allowance — — Other, net — Provision for income taxes $ $ $ $ The interim effective tax rate for the three and six months ended December 31, 2016 was positively impacted by foreign tax expense not recognized due to full valuation allowances recorded on certain foreign entities. Additionally, the excess tax benefit for the greater allowable deduction for stock-based compensation for tax purposes compared to the book expense related to the Company’s restricted stock unit plans (See Note 8 – Stock-based Compensation ) was recorded as a discrete permanent benefit during the period. The interim effective tax rate continues to be negatively impacted by stock-based compensation expense related to the common units of Communications Infrastructure Investments, LLC (“CII”). This quarter ended December 31, 2016 is expected to be the final period for stock-based compensation expense associated with the common units of CII. The Company files income tax returns in various federal, state, and local jurisdictions including the United States, United Kingdom and Canada. 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.

Equity

Equity	6 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Equity	(7) EQUITY During the six months ended December 31, 2016, the Company recorded a $60.2 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, 2016
Stock-Based Compensation [Abstract]
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, 2016 2015 2016 2015 (in millions) Included in: Operating costs $ $ $ $ Selling, general and administrative expenses Total stock-based compensation expense $ $ $ $ CII common units $ $ $ $ Part A restricted stock units Part B restricted stock units Part C restricted stock units Total stock-based compensation expense $ $ $ $ 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 CII common units. During the three and six months ended December 31, 2015, the Company recognized $26.4 million and $45.9 million, respectively, of stock-based compensation expense related to vesting of CII common units. During the three months ended December 31, 2016, the CII common units became fully vested and as such, there is no unrecognized compensation cost associated with CII common units as of December 31, 2016. 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 restricted stock units or “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, all 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 a 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 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. Upon vesting, the RSUs convert to an equal number of shares of the Company’s common stock. 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. During the three and six months ended December 31, 2015, the Company recognized $10.2 million and $20.2 million, respectively, of compensation expense associated with the vested portion of the Part A awards. The December 2016 and June 2016 quarterly awards were recorded as liabilities totaling $3.0 million and $2.0 million, as of December 31, 2016 and June 30, 2016, 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 “Other long-term 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, 2016, the remaining unrecognized compensation cost to be expensed over the remaining vesting period for Part A awards is $32.6 million. The following table summarizes the Company’s Part A RSU activity for the six months ended December 31, 2016: Number of Part A Weighted average Weighted average Outstanding at July 1, 2016 $ Granted Vested Forfeited n/a Outstanding at December 31, 2016 $ 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, assuming continuous employment through the end of the measurement period. 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, 2016: Number of Part B Weighted average Weighted average Outstanding at July 1, 2016 $ Granted Vested Forfeited n/a Outstanding at December 31, 2016 $ The table below reflects the total Part B RSUs granted during Fiscal 2017 and 2016, the maximum eligible shares of the Company’s 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 three months ended December 31, September 30, Part B RSUs granted Maximum eligible shares of the Company's common stock Grant date fair value per Part B RSU $ $ During the three months ended June 30, March 31, December 31, September 30, Part B RSUs granted Maximum eligible shares of the Company's common stock Grant date fair value per Part B RSU $ $ $ $ Units converted to Company's common stock at vesting date n/a — The Company recognized stock-based compensation expense of $9.5 million and $15.7 million related to Part B awards for the three and six months ended December 31, 2016, respectively, and $6.0 million and $22.4 million for the three and six months ended December 31, 2015, respectively. 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 $17.7 million at December 31, 2016. 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, 2016, the Company’s independent directors were granted 11,230 and 21,841 Part C RSUs, respectively. During the three and six months ended December 31, 2015, the Company’s independent directors were granted 10,874 and 18,826 Part C RSUs, respectively. Part C RSUs vest in the same quarter that they are issued. 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. During the three and six months ended December 31, 2015, the Company recognized $0.3 million and $0.5 million, respectively, of compensation expense associated with the Part C RSUs.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Dec. 31, 2016
Fair Value Measurements [Abstract]
Fair Value Measurements	(9) FAIR VALUE MEASUREMENTS The Company’s financial instruments consist of cash and cash equivalents, restricted cash, trade receivables, accounts payable, interest rate swaps, 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, 2016 and June 30, 2016 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 discount, and was $2,320.9 million and $2,320.7 million as of December 31, 2016 and June 30, 2016, 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, 2016 and June 30, 2016 was estimated to be $2,425.5 million and $2,338.1 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 $1,820.3 million and $1,818.4 million as of December 31, 2016 and June 30, 2016, respectively. The Company’s Term Loan Facility accrues interest at variable rates based upon the one month, three month or six month LIBOR (with a LIBOR floor of 1.00%) plus a spread of 2.75%. Since management does not believe that the Company’s credit quality has changed significantly since the date when the Term Loan Facility was last amended on May 6, 2015, its carrying amount approximates fair value. Excluding any offsetting effect of the Company’s interest rate swaps, 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 $18.4 million. The Company’s interest rate swaps are valued using discounted cash flow techniques that use observable market inputs, such as LIBOR-based yield curves, forward rates, and credit ratings. Changes in the fair value of the interest rate swaps of $0.8 million and $1.5 million were recorded as a decrease to interest expense during the three and six months ended December 31, 2016, respectively, and $1.0 million and $0.6 million were recorded as a decrease to interest expense during the three and six months ended December 31, 2015, respectively. A hypothetical increase in LIBOR rates of 100 basis points would favorably increase the fair value of the interest rate swaps by approximately $3.2 million. As of December 31, 2016 and June 30, 2016, there was no balance outstanding under the Company's Revolver. Financial instruments measured at fair value on a recurring basis are summarized below: Level December 31, 2016 June 30, 2016 Liabilities Recorded at Fair Value in the Financial Statements: (in millions) Interest rate swap Level 2 $ $

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Dec. 31, 2016
Commitments And Contingencies [Abstract]
Commitments And Contingencies	(10) COMMITMENTS AND CONTINGENCIES Purchase commitments At December 31, 2016, the Company was contractually committed for $295.9 million of capital expenditures for construction materials and purchases of property and equipment. 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. Electric Lightwave Acquisition On November 29, 2016, the Company entered into an Agreement and Plan of Merger to acquire 100% of the equity interest in Electric Lightwave Parent, Inc. (“Electric Lightwave”) for cash consideration of $1.42 billion, subject to customary working capital and other adjustments. Electric Lightwave, which provides infrastructure and telecom services primarily in the Western United States, has 8,100 route miles of long haul fiber and 4,000 miles of dense metro fiber, with on-net connectivity to more than 3,100 enterprise buildings and 100 data centers. The Company expects the Electric Lightwave acquisition to close during the quarter ended March 31, 2017, subject to standard closing conditions and regulatory approval. The Electric Lightwave acquisition will be funded with proceeds from the Incremental Term Loan and 2027 Unsecured Notes (both defined in Note 13 – Subsequent Events ) 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, 2016
Related Party Transactions [Abstract]
Related Party Transactions	(11) RELATED PARTY TRANSACTIONS In May 2016, CII sold Onvoy, LLC and its subsidiaries (“OVS”) to an entity that has a material ownership interest in the Company. The Company continues to have ongoing contractual relationships with OVS, whereby the Company provides OVS and its subsidiaries with bandwidth capacity and OVS provides the Company and its subsidiaries with voice services. 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 OVS for the periods presented: Three Months Ended December 31, Six Months Ended December 31, 2016 2015 2016 2015 (in millions) Revenues $ $ $ $ Operating costs $ $ $ $ As of December 31, 2016 and June 30, 2016, the Company had $0.1 million and nil outstanding balances due from OVS. 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, 2016, the Company reimbursed Mr. Caruso $0.2 million and $0.4 million, respectively, and during the three and six months ended December 31, 2015 reimbursed $0.2 million and $0.3 million, respectively, for his business use of the aircraft.

Segment Reporting

Segment Reporting	6 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Segment Reporting	(12) 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 dark fiber solutions, network connectivity, colocation and cloud infrastructure, Zayo Canada and other services are comprised of various related product groups generally defined around the type of service the customer is buying, referred to as Strategic Product Groups ("SPG" or "SPGs"). Each SPG is responsible for the revenue, costs and associated capital expenditures of their respective services. The SPGs enable sales, make pricing and product decisions, engineer networks and deliver services to customers, and support customers for their specific telecom and Internet infrastructure services. The segment managers report directly to the CODM, and it is the financial results of those segments that are evaluated and drive the resource allocation decisions made by the CODM. The Company’s segments are further described below: Dark Fiber Solutions. Through the Dark Fiber Solutions segment, the Company provides raw bandwidth infrastructure to customers that require more control of their internal networks. These services include dark fiber 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 services provide direct fiber connections to cell towers, small cells, hub sites, and mobile switching centers. Dark 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 Dark Fiber Solutions segment tend to range from three to twenty years. Network Connectivity. The Network Connectivity segment provides bandwidth infrastructure solutions over the Company’s metro, regional, and long-haul fiber networks where it uses optronics to light the fiber and the Company’s customers pay for access based on the amount and type of bandwidth they purchase. The Company’s services within this segment include wavelength, Ethernet, IP and SONET. The Company targets customers who require a minimum of 10G of bandwidth across their networks. Network Connectivity customers include carriers, financial services companies, healthcare, government institutions, education institutions and other enterprises. The contract terms in this segment tend to range from two to five years. Colocation and Cloud Infrastructure. The Colocation and Cloud Infrastructure segment provides data center infrastructure solutions to a broad range of enterprise, carrier, content and cloud customers. The Company’s services within this segment include colocation, interconnection, cloud, hosting and managed services, such as security and remote hands offerings. Solutions range in size from single cabinet and server support to comprehensive international outsourced IT infrastructure environments. The Company’s data centers also support a large component of the Company’s networking equipment for the purpose of aggregating and distributing data, voice, Internet, and video traffic. The contract terms in this segment tend to range from two to five years Zayo Canada. The Zayo Canada segment is comprised of the recently acquired business of Allstream (see Note 2 – Acquisitions ). The services provided by this segment include legacy dark fiber, network connectivity, cloud and colocation infrastructure, voice, unified communications, managed security services and small and medium businesses (“SMB”) of Allstream. Voice provides a full range of local voice services 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 services such as telephony (including IP telephony), instant messaging and video conferencing with non-real-time communication services, 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 devices, media types and geographies. Managed security services provide proactive services and solutions designed to enable organizations to operate in an environment of constantly evolving threats from organized cyber-crime. The service provides real-time threat analysis and correlation of information security threats, response and mitigations services, secure access to the internet and the cloud, information risk and compliance services, and management of the IT security envelope. Zayo Canada provides services to over 26,000 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 services 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. Services are typically provided 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 equipment sales. Revenues for all of the Company’s products are included in one of the Company’s segments. 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. As of and for the three months ended December 31, 2016 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Revenue from external customers $ $ $ $ $ $ — $ Segment Adjusted EBITDA — Capital expenditures — — As of and for the six months ended December 31, 2016 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Revenue from external customers $ $ $ $ $ $ — $ Segment Adjusted EBITDA — Total assets Capital expenditures — — As of and for the three months ended December 31, 2015 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Revenue from external customers $ $ $ $ — $ $ — $ Segment Adjusted EBITDA — — Total assets — Capital expenditures — — — As of and for the six months ended December 31, 2015 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Revenue from external customers $ $ $ $ — $ $ — $ Segment Adjusted EBITDA — — Capital expenditures — — — As of June 30, 2016 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Total assets $ $ $ $ $ $ $ Reconciliation from Total Segment Adjusted EBITDA to income/(loss) from operations before taxes: For the three months ended December 31, 2016 2015 (in millions) Total Segment Adjusted EBITDA $ $ Interest expense Depreciation and amortization expense Transaction costs Stock-based compensation Foreign currency loss on intercompany loans Non-cash loss on investments Income from operations before income taxes $ $ For the six months ended December 31, 2016 2015 (in millions) Total Segment Adjusted EBITDA $ $ Interest expense Depreciation and amortization expense Transaction costs Stock-based compensation Foreign currency loss on intercompany loans Non-cash loss on investments Income/(loss) from operations before income taxes $ $

Subsequent Events

Subsequent Events	6 Months Ended
	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	(13) SUBSEQUENT EVENTS On January 19, 2017, the Company 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 million tranche that bears interest at a rate of LIBOR plus 2.0%, with no minimum LIBOR rate and a maturity date of four years from incurrence, which represents a downward adjustment of 75 basis points along with the removal of the previous LIBOR floor, and a second $1.35 billion tranche 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, the Company added a new $650.0 million term loan tranche under the Credit Agreement (the “$650 million Term Loan”), which will be available to the Company to borrow in connection with the Company’s announced acquisition of Electric Lightwave. The $650 million Term Loan will be issued at a price of 99.75% and will bear 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. No other terms of the Credit Agreement were amended. On January 27, 2017, the Company completed a private offering of $800.0 million aggregate principal amount of 5.75% senior unsecured notes due in 2027 (the “2027 Unsecured Notes”). The net proceeds of the $650 million Term Loan and 2027 Unsecured Notes will be used to fund the consideration to be paid in connection with the Company’s acquisition of Electric Lightwave. Any excess net proceeds will be used for general corporate purposes, which may include repayment of other indebtedness, acquisitions, working capital and capital expenditures. In the event the merger agreement governing the acquisition of Electric Lightwave is terminated or the acquisition is not consummated on or prior to May 29, 2017, the Company will be required to redeem the 2027 Unsecured Notes pursuant to a special mandatory redemption at a redemption price equal to the offering price of the 2027 Unsecured Notes, plus accrued and unpaid interest to, but not including, the redemption date.

Business and Basis of Present21

Business and Basis of Presentation (Policies)	6 Months Ended
	Dec. 31, 2016
Business and Basis of Presentation [Abstract]
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 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 consolidated financial statements should, therefore, be read in conjunction with the consolidated financial statements and notes thereto for the year ended June 30, 2016 included in the Company’s Annual Report on Form 10-K for the year ended June 30, 2016. 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. Certain amounts in the prior period financial statements have been condensed to conform to the current period presentation and had no impact on reported net income or losses. The results of operations for the three and six months ended December 31, 2016 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 ended June 30, 2016 as “Fiscal 2016” and the fiscal year ending June 30, 2017 as “Fiscal 2017.”
Earnings or Loss per Share	Earnings or Loss per Share Basic earnings or loss per share attributable to the Company’s common shareholders is computed by dividing net earnings or loss attributable to common shareholders by the weighted average number of common shares outstanding for the period. Diluted earnings or loss 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. No such items were included in the computation of diluted loss per share for the three and six months ended December 31, 2015 as the Company incurred a loss from operations in that period and the effect of inclusion would have been anti-dilutive. The effect of 2.1 million and 2.0 million incremental shares attributable to the release of Part A and Part B units upon vesting (treasury method) were included in the computation of diluted income per share for the three and six months ended December 31, 2016, respectively.
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 and estimating the 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 January 2017, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business.” The new standard provides guidance for evaluating whether transactions should be accounted for as acquisitions of assets or businesses. The standard is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted for transactions for which the acquisition date occurs before the issuance date or effective date, only when the transaction has not been reported in financial statements that have been issued or made available for issuance. The Company has elected to early adopt the standard as of January 1, 2017 and will apply the provisions of this standard for acquistions consummated subsequent to that date. 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 , 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. Early adoption is permitted. The new 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 is evaluating the effect that ASU 2016-02 will have on its consolidated financial statements and related disclosures. The Company has not yet selected a transition method nor has it determined the effect of the standard on its ongoing financial reporting. On March 30, 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , which is intended to improve the accounting for share-based payment transactions as part of the FASB’s simplification initiative. The ASU changes five aspects of the accounting for share-based payment award transactions that will affect public companies, including: (1) accounting for income taxes; (2) classification of excess tax benefits on the statement of cash flows; (3) forfeitures; (4) minimum statutory tax withholding requirements; and (5) classification of employee taxes paid on the statement of cash flows when an employer withholds shares for tax-withholding purposes. The Company early-adopted ASU 2016-09 effective July 1, 2016. Excess tax benefits for share-based payments are now recognized against income tax expense rather than additional paid-in capital and are included in operating cash flows rather than financing cash flows. The recognition of excess tax benefits have been applied prospectively and prior periods have not been adjusted. The Company had $4.3 million of excess tax benefits for the six months ended December 31, 2016. In addition, the Company elected to change its accounting policy to account for forfeitures as they occur. The change was applied on a modified retrospective basis with a cumulative effect adjustment to accumulated deficit of $1.7 million as of July 1, 2016. Amendments related to minimum statutory tax withholding requirements and the classification of employee taxes paid on the statement of cash flows when an employer withholds shares for tax-withholding purposes have been adopted prospectively and did not have a material impact on the condensed consolidated financial statements. 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 in 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. Early adoption is 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. The Company is evaluating the effect that ASU 2014-09 will have on the Company and its consolidated financial statements and related disclosures. The Company has not yet selected a transition method nor has it determined the effect of the standard on its ongoing financial reporting

Acquisitions (Tables)

Acquisitions (Tables)	6 Months Ended
	Dec. 31, 2016
Acquisitions [Abstract]
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: Santa Clara Data Acquisition date October 3, 2016 (in millions) Property and equipment $ Intangibles Total assets acquired Capital lease obligations Total liabilities assumed Total purchase consideration $ The table below reflects the Company's estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2016 acquisitions: Clearview Allstream Viatel Dallas Data Acquisition date April 1, 2016 January 15, 2016 December 31, 2015 December 31, 2015 (in millions) Cash $ — $ $ $ — Other current assets — Property and equipment Deferred tax assets, net — — Intangibles — Goodwill — — Other assets — Total assets acquired Current liabilities — Deferred revenue — Deferred tax liability, net — — — Other liabilities — Total liabilities assumed — Net assets acquired Less cash acquired — — Net consideration paid $ $ $ $
Schedule of Pro-Forma Financial Information	Three Months Ended December 31, Six Months Ended December 31, 2016 2015 2016 2015 (in millions) Revenue $ $ $ $ Net income/(loss) $ $ $ $

Goodwill (Tables)

Goodwill (Tables)	6 Months Ended
	Dec. 31, 2016
Goodwill [Abstract]
Schedule of Goodwill	The following reflects the changes in the carrying amount of goodwill during the six months ended December 31, 2016: Product Group As of June 30, 2016 Adjustments to Fiscal 2016 Acquisitions Foreign Currency As of December 31, 2016 (in millions) Dark Fiber $ $ $ $ Waves Sonet — Ethernet IP — MIG — — zColo Cloud — Other — Total $ $ $ $

Intangible Assets (Tables)

Intangible Assets (Tables)	6 Months Ended
	Dec. 31, 2016
Intangible Assets [Abstract]
Schedule of Intangible Assets	Gross Carrying Amount Accumulated Net (in millions) December 31, 2016 Finite-Lived Intangible Assets Customer relationships $ $ $ Underlying rights Total Indefinite-Lived Intangible Assets Certifications — Underlying Rights — Total $ $ $ June 30, 2016 Finite-Lived Intangible Assets Customer relationships $ $ $ Trade names — Underlying rights Total Indefinite-Lived Intangible Assets Certifications — Underlying Rights — Total $ $ $

Long-Term Debt (Tables)

Long-Term Debt (Tables)	6 Months Ended
	Dec. 31, 2016
Long-Term Debt [Abstract]
Schedule of Debt	December 31, June 30, 2016 2016 (in millions) Term Loan Facility due 2021 $ $ 6.00% Senior Unsecured Notes due 2023 6.375% Senior Unsecured Notes due 2025 Total debt obligations Unamortized discount on Term Loan Facility Unamortized premium on 6.00% Senior Unsecured Notes due 2023 Unamortized discount on 6.375% Senior Unsecured Notes due 2025 Unamortized debt issuance costs Carrying value of debt $ $

Income Taxes (Tables)

Income Taxes (Tables)	6 Months Ended
	Dec. 31, 2016
Income Taxes [Abstract]
Schedule of Reconciliation of Income Tax Provision	Three months ended December 31, Six months ended December 31, 2016 2015 2016 2015 (in millions) Expected expense/(benefit) at the statutory rate $ $ $ $ Increase/(decrease) due to: Non-deductible stock-based compensation Excess tax benefit on stock-based compensation — — State income taxes benefit, net of federal benefit Transactions costs not deductible for tax purposes Change in tax rates — — — Foreign tax rate differential Foreign entities with valuation allowance — — Other, net — Provision for income taxes $ $ $ $

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Dec. 31, 2016
Schedule of Employee Service Share-based Compensation Allocation of Recognized Period Costs	Three Months Ended December 31, Six Months Ended December 31, 2016 2015 2016 2015 (in millions) Included in: Operating costs $ $ $ $ Selling, general and administrative expenses Total stock-based compensation expense $ $ $ $ CII common units $ $ $ $ Part A restricted stock units Part B restricted stock units Part C restricted stock units Total stock-based compensation expense $ $ $ $
Summary Of Part B RSU Issuance	Number of Part B Weighted average Weighted average Outstanding at July 1, 2016 $ Granted Vested Forfeited n/a Outstanding at December 31, 2016 $ The table below reflects the total Part B RSUs granted during Fiscal 2017 and 2016, the maximum eligible shares of the Company’s 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 three months ended December 31, September 30, Part B RSUs granted Maximum eligible shares of the Company's common stock Grant date fair value per Part B RSU $ $ During the three months ended June 30, March 31, December 31, September 30, Part B RSUs granted Maximum eligible shares of the Company's common stock Grant date fair value per Part B RSU $ $ $ $ Units converted to Company's common stock at vesting date n/a —
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, 2016: Number of Part A Weighted average Weighted average Outstanding at July 1, 2016 $ Granted Vested Forfeited n/a Outstanding at December 31, 2016 $
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, 2016: Number of Part B Weighted average Weighted average Outstanding at July 1, 2016 $ Granted Vested Forfeited n/a Outstanding at December 31, 2016 $

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Dec. 31, 2016
Fair Value Measurements [Abstract]
Schedule of Financial Instruments Measured at Fair Value on a Recurring Basis	Level December 31, 2016 June 30, 2016 Liabilities Recorded at Fair Value in the Financial Statements: (in millions) Interest rate swap Level 2 $ $

Related Party Transactions (Tab

Related Party Transactions (Tables)	6 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Revenue and Expense Transactions Recognized	Three Months Ended December 31, Six Months Ended December 31, 2016 2015 2016 2015 (in millions) Revenues $ $ $ $ Operating costs $ $ $ $

Segment Reporting (Tables)

Segment Reporting (Tables)	6 Months Ended
	Dec. 31, 2016
Segment Reporting [Abstract]
Summary of Financial Information by Segments	As of and for the three months ended December 31, 2016 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Revenue from external customers $ $ $ $ $ $ — $ Segment Adjusted EBITDA — Capital expenditures — — As of and for the six months ended December 31, 2016 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Revenue from external customers $ $ $ $ $ $ — $ Segment Adjusted EBITDA — Total assets Capital expenditures — — As of and for the three months ended December 31, 2015 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Revenue from external customers $ $ $ $ — $ $ — $ Segment Adjusted EBITDA — — Total assets — Capital expenditures — — — As of and for the six months ended December 31, 2015 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Revenue from external customers $ $ $ $ — $ $ — $ Segment Adjusted EBITDA — — Capital expenditures — — — As of June 30, 2016 Dark Fiber Network Colocation and Cloud Zayo Other Corp/ Total (in millions) Total assets $ $ $ $ $ $ $
Reconciliation from Total Segment Adjusted EBITDA to income/(loss) from operations before taxes	For the three months ended December 31, 2016 2015 (in millions) Total Segment Adjusted EBITDA $ $ Interest expense Depreciation and amortization expense Transaction costs Stock-based compensation Foreign currency loss on intercompany loans Non-cash loss on investments Income from operations before income taxes $ $ For the six months ended December 31, 2016 2015 (in millions) Total Segment Adjusted EBITDA $ $ Interest expense Depreciation and amortization expense Transaction costs Stock-based compensation Foreign currency loss on intercompany loans Non-cash loss on investments Income/(loss) from operations before income taxes $ $

Business and Basis of Present31

Business and Basis of Presentation (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended	6 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Incremental shares attributable to the release of Part A and Part B units upon vesting included in the computation of diluted income per share	2.1	2
Excess tax benefit from stock-based compensation			$ 7.9
Accounting Standards Update 2016-09 [Member]
Excess tax benefit from stock-based compensation		$ 4.3
Cumulative effect adjustment resulting from adoption of ASU 2016-09 (Note 1)		$ 1.7

Acquisitions (Narrative) (Detai

Acquisitions (Narrative) (Details) € in Millions, CAD in Millions, $ in Millions	Oct. 03, 2016USD ($)ft²paymentMW	Apr. 01, 2016USD ($)ft²item	Jan. 15, 2016CADbuildingitemmi	Jan. 15, 2016USD ($)buildingitemmi	Dec. 31, 2015EUR (€)ft²	Dec. 31, 2015USD ($)ft²	Sep. 30, 2016USD ($)	Dec. 31, 2015USD ($)ft²	Dec. 31, 2016USD ($)item	Dec. 31, 2015USD ($)ft²
Business Acquisition [Line Items]
Number of business combinations completed | item									39
Net consideration paid									$ 1.3	$ 117.7
Acquisition related costs							$ 6.2	$ 3.3	9.2	$ 3.3
Santa Clara Data Center
Business Acquisition [Line Items]
Net consideration paid	$ 12.8
Net consideration paid	$ 11.3
Number of quarterly payments | payment	10
Amount of quarterly payments	$ 1.3
Amount of cash consideration to be paid									11.5
Acquired facility size (in square feet) | ft²	26,900
Acquired megawatts of critical power | MW	3
Clearview
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired		100.00%
Net consideration paid		$ 18.3
Net consideration paid		$ 18.3
Acquired facility size (in square feet) | ft²		30,000
Purchase price, held in escrow		$ 1.1
Number of data centers | item		2
Allstream
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired				100.00%
Net consideration paid			CAD 422.9	$ 297.6
Net consideration paid				297.6
Working capital and other liabilities assumed in the acquisition				$ 29.6
Additional Route Miles Acquired | mi			18,000	18,000
Long-Haul Fiber Network Acquired | mi			12,500	12,500
Metro Fiber Network Acquired | mi			5,500	5,500
Network concentrating net buildings | building			3,300	3,300
Number of metropolitan markets | item			5	5
Other post retirement benefits plan liability assumed				$ 8.3					12.9
Viatel
Business Acquisition [Line Items]
Business acquisition, percentage of voting interests acquired					100.00%	100.00%		100.00%		100.00%
Net consideration paid					€ 92.9	$ 101.2
Net consideration paid						101.2
Refund of escrow reflected as a cash inflow from investing activities									$ 1.5
Dallas Data Center
Business Acquisition [Line Items]
Net consideration paid						16.6
Net consideration paid						$ 16.6
Acquired facility size (in square feet) | ft²					36,000	36,000		36,000		36,000

Acquisitions (Schedule of Acqui

Acquisitions (Schedule of Acquisition) (Details) - USD ($) $ in Millions	Oct. 03, 2016	Apr. 01, 2016	Jan. 15, 2016	Dec. 31, 2015	Dec. 31, 2016	Jun. 30, 2016
Business Acquisition [Line Items]
Goodwill					$ 1,196.9	$ 1,214.5
Santa Clara Data Center
Business Acquisition [Line Items]
Property and equipment	$ 35.1
Intangibles	2.8
Total assets acquired	37.9
Capital lease obligations	26.6
Total liabilities assumed	26.6
Net consideration paid	$ 11.3
Clearview
Business Acquisition [Line Items]
Other current assets		$ 0.6
Property and equipment		15.4
Deferred tax assets, net		0.2
Intangibles		9.8
Goodwill		3.8
Other assets		0.3
Total assets acquired		30.1
Current liabilities		1.1
Deferred revenue		0.4
Other liabilities		10.3
Total liabilities assumed		11.8
Net assets acquired		18.3
Net consideration paid		$ 18.3
Allstream
Business Acquisition [Line Items]
Cash			$ 2.9
Other current assets			95.6
Property and equipment			266.3
Deferred tax assets, net			3.8
Intangibles			64.5
Other assets			4.5
Total assets acquired			437.6
Current liabilities			63.2
Deferred revenue			46.9
Other liabilities			27
Total liabilities assumed			137.1
Net assets acquired			300.5
Less cash acquired			(2.9)
Net consideration paid			$ 297.6
Viatel
Business Acquisition [Line Items]
Cash				$ 3.5
Other current assets				7.3
Property and equipment				174
Goodwill				9.5
Other assets				2
Total assets acquired				196.3
Current liabilities				18.8
Deferred revenue				58.5
Deferred tax liability, net				8.6
Other liabilities				5.7
Total liabilities assumed				91.6
Net assets acquired				104.7
Less cash acquired				(3.5)
Net consideration paid				101.2
Dallas Data Center
Business Acquisition [Line Items]
Property and equipment				12.2
Intangibles				4.4
Total assets acquired				16.6
Net assets acquired				16.6
Net consideration paid				$ 16.6

Acquisitions (Schedule of Pro-F

Acquisitions (Schedule of Pro-Forma Financial Information) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Acquisitions [Abstract]
Revenue	$ 506.7	$ 496	$ 1,013	$ 990.2
Net income/(loss)	$ 19.8	$ (9.9)	$ 35.9	$ (24.2)

Goodwill (Schedule Of Goodwill)

Goodwill (Schedule Of Goodwill) (Details) $ in Millions	6 Months Ended
	Dec. 31, 2016USD ($)
Goodwill [Line Items]
Goodwill, beginning Balance	$ 1,214.5
Adjustments to acquisitions	(3.6)
Foreign Currency Translation and Other	(14)
Goodwill, ending balance	1,196.9
Dark Fiber [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	295.1
Adjustments to acquisitions	1.7
Foreign Currency Translation and Other	(9.6)
Goodwill, ending balance	287.2
Waves [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	258.3
Adjustments to acquisitions	(2.7)
Foreign Currency Translation and Other	(3.3)
Goodwill, ending balance	252.3
Sonet [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	51.3
Foreign Currency Translation and Other	(0.1)
Goodwill, ending balance	51.2
Ethernet [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	104.3
Adjustments to acquisitions	(0.5)
Foreign Currency Translation and Other	(0.2)
Goodwill, ending balance	103.6
IP [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	87.5
Foreign Currency Translation and Other	(0.4)
Goodwill, ending balance	87.1
MIG [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	73.6
Goodwill, ending balance	73.6
zColo [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	268.8
Adjustments to acquisitions	(2)
Foreign Currency Translation and Other	(0.2)
Goodwill, ending balance	266.6
Cloud [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	60
Adjustments to acquisitions	(0.1)
Goodwill, ending balance	59.9
Other [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	15.6
Foreign Currency Translation and Other	(0.2)
Goodwill, ending balance	$ 15.4

Intangible Assets (Schedule of

Intangible Assets (Schedule of Identifiable Acquisition Related Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Jun. 30, 2016
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount	$ 1,150.4	$ 1,145.4
Accumulated Amortization	(265.3)	(229.3)
Total Net	885.1	916.1
Intangible Assets, Gross (Excluding Goodwill)	1,168	1,164.2
Intangible Assets, Net	902.7	934.9
Certifications [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount, Indefinite-lived Intangibles	3.5	3.5
Indefinite-Lived Underlying Rights [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount, Indefinite-lived Intangibles	14.1	15.3
Customer relationships [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount	1,148.8	1,143.6
Accumulated Amortization	(264.9)	(228.8)
Total Net	883.9	914.8
Trade names [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount		0.2
Accumulated Amortization		(0.2)
Finite-Lived Underlying rights [Member]
Schedule Of Intangible Assets Net Excluding Goodwill [Line Items]
Gross Carrying Amount	1.6	1.6
Accumulated Amortization	(0.4)	(0.3)
Total Net	$ 1.2	$ 1.3

Long-Term Debt (Summary of Long

Long-Term Debt (Summary of Long-Term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Jun. 30, 2016
Debt Instrument [Line Items]
Debt obligations	$ 4,167.4	$ 4,167.4
Unamortized discount	(17.1)	(19)
Unamortized debt issuance costs	(49.9)	(53.8)
Carrying value of debt	4,091.3	4,085.3
6.00% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Unamortized premium	$ 5.9	6.3
Interest rate	6.00%
6.375% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Unamortized discount	$ (15)	(15.6)
Interest rate	6.375%
Term Loan Facility due 2021 [Member]
Debt Instrument [Line Items]
Debt obligations	$ 1,837.4	1,837.4
Carrying value of debt	1,820.3	1,818.4
Unsecured Debt [Member] | 6.00% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Debt obligations	1,430	1,430
Unsecured Debt [Member] | 6.375% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Debt obligations	$ 900	$ 900

Long-Term Debt (Narrative) (Det

Long-Term Debt (Narrative) (Details) - USD ($) $ in Millions	Jul. 22, 2016	Apr. 14, 2016	Jan. 15, 2016	May 06, 2015	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Aug. 13, 2012
Debt Instrument [Line Items]
Discount on debt					$ 17.1	$ 19		$ 17.1
Redemption of debt									$ 8.3
Loss on extinguishment of debt						11.4
Secured debt ratio					4.50			4.50
Debt issuance costs					$ 49.9	53.8		$ 49.9
Accumulated amortization					40.2	35.8		40.2
Interest expense associated with the amortization of debt issuance costs					2.2		$ 2.5	4.4	5
Fair value of interest rate swaps					1.5	$ 3		1.5
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative, notional amount										$ 750
Derivative, fixed interest rate										1.67%
Derivative, floor rate										1.25%
Change in fair value of interest rate swap					$ 0.8		$ 1	$ 1.5	$ 0.6
Secured Debt [Member] | Revolver [Member]
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity				$ 450
Weighted average interest rate (including margins)					3.80%	3.40%		3.80%
Remaining borrowing capacity					$ 442.7			$ 442.7
Percentage of excess revolver committed to debt payments								35.00%
Secured debt ratio					5.25			5.25
Secured Debt [Member] | Letter Of Credit [Member]
Debt Instrument [Line Items]
Line of credit facility maximum borrowing capacity				$ 50
Unused commitment, percentage				0.25%
Outstanding letters of credit					$ 7.3			$ 7.3
Term Loan Facility due 2021 [Member]
Debt Instrument [Line Items]
Payment towards principal				$ 5.1
Percentage of excess cash flows committed to debt payments				50.00%
Weighted average interest rate (including margins)					3.75%	3.90%		3.75%
Redemption of debt		$ 196
Loss on extinguishment of debt		2.1
Incremental Term Loan [Member]
Debt Instrument [Line Items]
Line of credit facility increase to borrowing capacity			$ 400
Priced percent of additional line of credit			99.00%
Discount on debt			$ 4.8
Credit Agreement
Debt Instrument [Line Items]
Debt issuance costs					$ 90.1			$ 90.1
Minimum | Secured Debt [Member] | Revolver [Member]
Debt Instrument [Line Items]
Unused commitment, percentage				0.25%
Maximum
Debt Instrument [Line Items]
Total indebtedness ratio					6			6
Maximum | Secured Debt [Member] | Revolver [Member]
Debt Instrument [Line Items]
Unused commitment, percentage				0.375%
6.00% Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Interest rate of debt redeemed					6.00%			6.00%
6.375% Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Discount on debt					$ 15	$ 15.6		$ 15
Interest rate of debt redeemed					6.375%			6.375%
6.375% New Senior Notes due 2025 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Discount on debt		15.9
Debt instrument, face amount		$ 550
Priced percent of new debt		97.10%
10.125% Senior Notes due 2020 [Member] | Unsecured Debt [Member]
Debt Instrument [Line Items]
Redemption of debt		$ 325.6
Interest rate of debt redeemed		10.125%
Redemption premium and accrued interest included in redemption amount		$ 20.3
LIBOR | Term Loan Facility due 2021 [Member]
Debt Instrument [Line Items]
Interest rate decrease				0.25%
Spread on interest rate				2.75%				2.75%
LIBOR | Incremental Term Loan [Member]
Debt Instrument [Line Items]
Interest rate decrease	0.75%
Spread on interest rate	2.75%		3.50%
LIBOR | Minimum | Secured Debt [Member] | Letter Of Credit [Member]
Debt Instrument [Line Items]
Spread on interest rate				2.00%
LIBOR | Minimum | Term Loan Facility due 2021 [Member]
Debt Instrument [Line Items]
Spread on interest rate				1.00%
LIBOR | Minimum | Incremental Term Loan [Member]
Debt Instrument [Line Items]
Spread on interest rate	1.00%		1.00%
LIBOR | Maximum | Secured Debt [Member] | Letter Of Credit [Member]
Debt Instrument [Line Items]
Spread on interest rate				3.00%

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Income Tax Provision) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
Expected expense/(benefit) at the statutory rate	$ 7.1	$ 0.1	$ 14.8	$ (4.3)
Non-deductible stock-based compensation	2.4	10	4	17.4
Excess tax benefit on stock-based compensation	(5.3)		(3.6)
State income taxes benefit, net of federal benefit	0.8	0.1	1.5	(0.5)
Transaction costs not deductible for tax purposes	0.2	0.5	0.3	0.5
Change in tax rates			(1.7)
Foreign tax rate differential	0.4	0.4	(0.3)	0.3
Foreign entities with valuation allowance	(4.4)		(6.7)
Other, net	(1)		(1.5)	0.4
Provision/(benefit) for income taxes	$ 0.2	$ 11.1	$ 6.8	$ 13.8

Equity (Narrative) (Details)

Equity (Narrative) (Details) $ in Millions	6 Months Ended
	Dec. 31, 2016USD ($)
Equity [Abstract]
Increase in additional paid-in capital associated with stock-based compensation expense	$ 60.2

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, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 34.5	$ 42.9	$ 66.5	$ 89
Operating Costs [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	3.3	5.1	6.6	11.8
Selling, General and Administrative Expenses [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	31.2	37.8	59.9	77.2
Part A Restricted Stock Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	18.8	10.2	40.1	20.2
Part B Restricted Stock Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	9.5	6	15.7	22.4
Part C Restricted Stock Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	0.3	0.3	0.6	0.5
CII [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 5.9	$ 26.4	$ 10.1	$ 45.9

Stock-Based Compensation (Narra

Stock-Based Compensation (Narrative) (Details) - USD ($) $ in Millions	Oct. 16, 2014	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized		981,817	1,030,185	1,606,332	1,463,733	1,449,860	1,426,812	981,817	1,449,860
Number of RSUs, Granted		191,015	200,425	312,516	284,773	282,074	272,813
PCIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive plan termination period	10 years
Part A Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common unit unvested		2,466,300		2,169,901				2,466,300
Unrecognized compensation cost		$ 32.6						$ 32.6
Award recorded as liability		$ 3		$ 2				$ 3
Number of RSUs, Granted								1,432,186
Part B Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common unit unvested		623,996		860,936				623,996
Unrecognized compensation cost		$ 17.7						$ 17.7
Number of RSUs, Granted								391,440
Part C Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of RSUs, Granted		11,230				10,874		21,841	18,826

Stock-Based Compensation (Sum43

Stock-Based Compensation (Summary Of Restricted Stock Units Activity) (Details) - $ / shares	3 Months Ended						6 Months Ended	12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2016	Jun. 30, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of RSUs, Granted	191,015	200,425	312,516	284,773	282,074	272,813
Weighted average grant-date fair value per share, Granted	$ 75.56	$ 47	$ 37.03	$ 25.12	$ 25.26	$ 17.83
Part A Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of RSUs, Outstanding beginning balance		2,169,901					2,169,901
Number of RSUs, Granted							1,432,186
Number of RSUs, Vested							(928,128)
Number of RSUs, Forfeited							(207,659)
Number of RSUs, Outstanding ending balance	2,466,300		2,169,901				2,466,300	2,169,901
Weighted average grant-date fair value per share, Outstanding beginning balance		$ 26.04					$ 26.04
Weighted average grant-date fair value per share, Granted							31.57
Weighted average grant-date fair value per share, vested							26.23
Weighted average grant-date fair value per share, Forfeited							0
Weighted average grant-date fair value per share, Outstanding ending balance	$ 29.07		$ 26.04				$ 29.07	$ 26.04
Weighted average remaining contractual term in months							7 months 24 days	7 months 27 days
Part B Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of RSUs, Outstanding beginning balance		860,936					860,936
Number of RSUs, Granted							391,440
Number of RSUs, Vested							(416,982)
Number of RSUs, Forfeited							(211,398)
Number of RSUs, Outstanding ending balance	623,996		860,936				623,996	860,936
Weighted average grant-date fair value per share, Outstanding beginning balance		$ 29.50					$ 29.50
Weighted average grant-date fair value per share, Granted							60.94
Weighted average grant-date fair value per share, vested							25.19
Weighted average grant-date fair value per share, Forfeited							0
Weighted average grant-date fair value per share, Outstanding ending balance	$ 51.99		$ 29.50				$ 51.99	$ 29.50
Weighted average remaining contractual term in months							5 months 21 days	6 months 6 days

Stock-Based Compensation (Sum44

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, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Part B RSUs granted	191,015	200,425	312,516	284,773	282,074	272,813
Maximum eligible shares of the Company's common stock	981,817	1,030,185	1,606,332	1,463,733	1,449,860	1,426,812	981,817
Grant date fair value	$ 75.56	$ 47	$ 37.03	$ 25.12	$ 25.26	$ 17.83
Units converted to the Company's common stock				475,446	40,182
Part B Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Part B RSUs granted							391,440
Grant date fair value							$ 60.94

Fair Value Measurements (Narrat

Fair Value Measurements (Narrative) (Details) - USD ($) $ in Millions	May 06, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value of the notes		$ 4,091.3		$ 4,091.3		$ 4,085.3
Hypothetical annual interest expense				18.4
Hypothetical increase to interest rate swap fair value		3.2		$ 3.2
Interest Rate Swap [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Hypothetical interest rate increase				100.00%
Change in fair value of interest rate swap		0.8	$ 1	$ 1.5	$ 0.6
Term Loan Facility due 2021 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value of the notes		1,820.3		$ 1,820.3		1,818.4
Hypothetical interest rate increase				1.00%
Term Loan Facility due 2021 [Member] | LIBOR
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Floor rate				1.00%
Spread on interest rate	2.75%			2.75%
Notes [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Carrying value of the notes		2,320.9		$ 2,320.9		2,320.7
Fair value of the notes		$ 2,425.5		$ 2,425.5		$ 2,338.1

Fair Value Measurements (Schedu

Fair Value Measurements (Schedule Of Financial Instruments Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Jun. 30, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of interest rate swaps	$ 1.5	$ 3
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value of interest rate swaps	$ 1.5	$ 3

Commitments and Contingencies (

Commitments and Contingencies (Narrative) (Details) $ in Millions	Nov. 29, 2016USD ($)buildingmiCenter	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Commitment And Contingencies [Line Items]
Purchase commitments		$ 295.9
Net consideration paid		$ 1.3	$ 117.7
Electric Lightwave [Member]
Commitment And Contingencies [Line Items]
Business acquisition, percentage of voting interests acquired	100.00%
Net consideration paid	$ 1,420
Long-Haul Fiber Network Acquired | mi	8,100
Metro Fiber Network Acquired | mi	4,000
Network concentrating net buildings | building	3,100
Number of data centers | Center	100

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, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Revenues	$ 1.5	$ 1.6	$ 3.1	$ 3.3
Operating costs	$ 0.1	$ 0.1	$ 0.2	$ 0.2

Related Party Transactions (Nar

Related Party Transactions (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Apr. 14, 2016
Unsecured Debt [Member] | 10.125% Senior Notes due 2020 [Member]
Related Party Transaction [Line Items]
Interest rate					10.125%
OVS [Member]
Related Party Transaction [Line Items]
Due from related parties	$ 0.1		$ 0.1
Dan Caruso [Member] | Aircraft Reimbursement [Member]
Related Party Transaction [Line Items]
Payable to related party settled	$ 0.2	$ 0.2	$ 0.4	$ 0.3

Segment Reporting (Narrative) (

Segment Reporting (Narrative) (Details)	6 Months Ended
	Dec. 31, 2016customeritem
Dark Fiber Solutions [Member] | Minimum
Segment Reporting Information [Line Items]
Number of dark fiber pairs leased to customers	2
Contract term	3 years
Dark Fiber Solutions [Member] | Maximum
Segment Reporting Information [Line Items]
Number of dark fiber pairs leased to customers	12
Contract term	20 years
Network Connectivity [Member] | Minimum
Segment Reporting Information [Line Items]
Contract term	2 years
Network Connectivity [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	5 years
Colocation and Cloud Infrastructure [Member] | Minimum
Segment Reporting Information [Line Items]
Contract term	2 years
Colocation and Cloud Infrastructure [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	5 years
Zayo Canada [Member]
Segment Reporting Information [Line Items]
Number of customers that can be serviced | customer	26,000
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, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Jun. 30, 2016
Segment Reporting Information [Line Items]
Revenue from external customers	$ 506.7	$ 369.6	$ 1,011.6	$ 736.4
Segment Adjusted EBITDA	263.4	218.9	524	434.3
Total assets	6,867.7	6,273.5	6,867.7	6,273.5	$ 6,727.5
Capital expenditures	213.6	172.4	421.9	331.6
Dark Fiber Solutions [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	150.4	137.7	298.8	272.7
Segment Adjusted EBITDA	110.5	99.1	218.7	195.7
Total assets	3,265.2	3,078.3	3,265.2	3,078.3	3,155
Capital expenditures	128.3	109.2	256.4	202.7
Network Connectivity [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	177.6	168.7	353.2	335.7
Segment Adjusted EBITDA	91.1	89.9	182.7	178.6
Total assets	1,903.4	1,900.7	1,903.4	1,900.7	1,901.8
Capital expenditures	48.3	48.1	97.2	94.8
Colocation and Cloud Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	66.7	58.5	130.8	116.8
Segment Adjusted EBITDA	33.9	29	66.1	57.4
Total assets	1,133.7	1,027.2	1,133.7	1,027.2	1,069.4
Capital expenditures	27.4	15.1	55.4	34.1
Zayo Canada [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	107.9		220.1
Segment Adjusted EBITDA	26.9		54.4
Total assets	463.1		463.1		477.6
Capital expenditures	9.6		12.9
Other [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	4.1	4.7	8.7	11.2
Segment Adjusted EBITDA	1	0.9	2.1	2.6
Total assets	31.8	34.4	31.8	34.4	33.4
Corp/Eliminations [Member]
Segment Reporting Information [Line Items]
Total assets	$ 70.5	$ 232.9	$ 70.5	$ 232.9	$ 90.3

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, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting [Abstract]
Total Segment Adjusted EBITDA	$ 263.4	$ 218.9	$ 524	$ 434.3
Interest expense	(53.7)	(51.2)	(107)	(105)
Depreciation and amortization expense	(131.4)	(113.7)	(269.9)	(230.8)
Transaction costs	(6.2)	(3.3)	(9.2)	(3.3)
Stock-based compensation	(34.5)	(42.9)	(66.5)	(89)
Foreign currency loss on intercompany loans	(17.4)	(7.1)	(28.6)	(17.8)
Non-cash loss on investments	(0.2)	(0.4)	(0.5)	(0.6)
Income/(loss) from operations before income taxes	$ 20	$ 0.3	$ 42.3	$ (12.2)

Subsequent Events (Narrative) (

Subsequent Events (Narrative) (Details) - Subsequent Event - USD ($) $ in Millions	Jan. 19, 2017	Jan. 27, 2017
5.75% Senior Notes Due in 2027 [Member]
Subsequent Event [Line Items]
Debt instrument, face amount		$ 800
Interest rate		5.75%
Term Loan Facility
Subsequent Event [Line Items]
Debt instrument, face amount	$ 1,850
Repriced percentage	99.75%
Term Loan Facility | Tranche One [Member]
Subsequent Event [Line Items]
Debt instrument, face amount	$ 500
Interest rate decrease (basis points)	0.75%
Term Loan Facility | Tranche One [Member] | LIBOR
Subsequent Event [Line Items]
Spread on interest rate	2.00%
Term Loan Facility | Tranche Two [Member]
Subsequent Event [Line Items]
Debt instrument, face amount	$ 1,350
Interest rate decrease (basis points)	0.25%
Term Loan Facility | Tranche Two [Member] | LIBOR
Subsequent Event [Line Items]
Spread on interest rate	2.50%
Term Loan Facility | Minimum | Tranche Two [Member] | LIBOR
Subsequent Event [Line Items]
Spread on interest rate	1.00%
Electric Lightwave [Member] | Term Loan Facility | $650 Million Term Loan [Member]
Subsequent Event [Line Items]
Debt instrument, face amount	$ 650
Issue price percentage	99.75%
Electric Lightwave [Member] | Term Loan Facility | $650 Million Term Loan [Member] | LIBOR
Subsequent Event [Line Items]
Spread on interest rate	2.50%
Electric Lightwave [Member] | Term Loan Facility | Minimum | $650 Million Term Loan [Member] | LIBOR
Subsequent Event [Line Items]
Spread on interest rate	1.00%