Zayo 10-Q 13 May 15 2015 Q3 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	9 Months Ended
	Mar. 31, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q3
Entity Registrant Name	ZAYO GROUP LLC
Entity Central Index Key	1502756
Current Fiscal Year End Date	-24
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding	0

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (USD $)	Mar. 31, 2015	Jun. 30, 2014
In Millions, unless otherwise specified
Current assets
Cash and cash equivalents	$157.90	$297.40
Trade receivables, net of allowance of $3.6 and $3.7 as of March 31, 2015 and June 30, 2014, respectively	94.5	59
Due from related parties	10.3	0.9
Prepaid expenses	36.2	25.6
Deferred income taxes, net	161	160.4
Other assets	4.9	2.4
Total current assets	464.8	545.7
Property and equipment, net	3,199.20	2,821.40
Intangible assets, net	969.3	709.7
Goodwill	1,194.20	845.3
Debt issuance costs, net	73.9	89.4
Other assets	58.7	37.8
Total assets	5,960.10	5,049.30
Current liabilities
Current portion of long-term debt	20.5	20.5
Accounts payable	34.8	27
Accrued liabilities	181.3	159.6
Accrued interest	24.2	57.1
Capital lease obligations, current	4	2.4
Deferred revenue, current	88.5	75.4
Total current liabilities	353.3	342
Long-term debt, non-current	3,720.10	3,219.70
Capital lease obligation, non-current	28.5	22.9
Deferred revenue, non-current	588.9	496.9
Stock-based compensation liability	1.9	392.4
Deferred income taxes, net	213.4	151.8
Other long-term liabilities	26.2	22.3
Total liabilities	4,932.30	4,648
Commitments and contingencies (Note 11)
Member's equity
Member's interest	1,551.20	728.9
Accumulated other comprehensive (loss)/income	-21.1	14.4
Accumulated deficit	-502.3	-342
Total member's equity	1,027.80	401.3
Total liabilities and member's equity	$5,960.10	$5,049.30

CONDENSED_CONSOLIDATED_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS (UNAUDITED) (Parenthetical) (USD $)	Mar. 31, 2015	Jun. 30, 2014
In Millions, unless otherwise specified
Statement Of Financial Position [Abstract]
Trade receivables allowance	$3.60	$3.70

Condensed_Consolidated_Stateme

Condensed Consolidated Statements Of Operations (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenue	$340.70	$283.20	$985.20	$831.60
Operating costs and expenses
Operating costs (excluding depreciation and amortization)	100.9	84.9	306	250.5
Selling, general and administrative expenses	83	96.6	271.7	260
Depreciation and amortization	100.1	84.2	293	246.9
Total operating costs and expenses	284	265.7	870.7	757.4
Operating income	56.7	17.5	114.5	74.2
Other expenses
Interest expense	-60.7	-49.1	-161	-150.9
Loss on extinguishment of debt	-54.9		-85.8	-1.9
Foreign currency (loss)/gain on intercompany loans	-13.2	0.1	-41.2	0.9
Other (expense)/income, net			-0.1	0.4
Total other expenses, net	-128.8	-49	-288.1	-151.5
Loss from operations before income taxes	-72.1	-31.5	-173.6	-77.3
(Benefit)/provision for income taxes	-18.4	12.1	-13.3	29.8
Net earnings/(loss)	($53.70)	($43.60)	($160.30)	($107.10)

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements Of Comprehensive Loss (Unaudited) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Comprehensive Income Net Of Tax [Abstract]
Net earnings/(loss)	($53.70)	($43.60)	($160.30)	($107.10)
Foreign currency translation adjustments	-14.5	1.6	-35.5	14.7
Comprehensive loss	($68.20)	($42)	($195.80)	($92.40)

Condensed_Consolidated_Stateme2

Condensed Consolidated Statement of Member's Equity (Unaudited) (USD $)	Total	Members Interest [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Deficit [Member]
In Millions
Balance at Jun. 30, 2014	$401.30	$728.90	$14.40	($342)
Capital Contributed	279.7	279.7
Reclassification of common unit liability to Member's interest	490.2	490.2
Stock-based compensation	52.4	52.4
Foreign currency translation adjustments	-35.5		-35.5
Net loss	-160.3			-160.3
Balance at Mar. 31, 2015	$1,027.80	$1,551.20	($21.10)	($502.30)

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (Unaudited)(USD ($))	9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2015	Mar. 31, 2014
			Latisys Holding LLC [Member]	Colo Facilities Atlanta [Member]	Access Communications, Inc [Member]
Cash flows from operating activities
Net earnings/(loss)	($160.30)	($107.10)
Adjustments to reconcile net loss to net cash provided by operating activities of continuing operations
Depreciation and amortization	293	246.9
Loss on extinguishment of debt	85.8	1.9
Non-cash interest expense	16.3	14.9
Non-cash loss on investments	0.5
Stock-based compensation	157.8	165.1
Amortization of deferred revenue	-52.9	-40.4
Additions to deferred revenue	123.6	112.6
Provision for bad debts	1.3	1.6
Foreign currency loss/(gain) on intercompany loans	41.2	-0.9
Deferred income taxes	-20	27.7
Changes in operating assets and liabilities, net of acquisitions
Due to/from related parties	-9.4	-1.7
Trade receivables	-18.5	24.1
Prepaid expenses	-3.5	-0.8
Accounts payable and accrued liabilities	-46.4	-33.1
Other assets and liabilities	-6.4	-9.2
Net cash provided by operating activities	402.1	401.6
Cash flows from investing activities
Purchases of property and equipment	-374.9	-265.9
Acquisition, net of cash acquired	-857.3	-101	-677.5	-52.5	-40.1
Other	-0.1	-0.3
Net cash used in investing activities	-1,232.20	-366.9
Cash flows from financing activities
Proceeds from debt	1,437.30	150
Proceeds from revolving credit facility		45
Equity contributions	279.7
Distribution to parent		-0.4
Principal payments on long-term debt	-939.8	-12.9
Payment of early redemption fees on debt extinguished	-62.6
Principal repayments on capital lease obligations	-2.4	-6.9
Payments on revolving credit facility		-45
Payment of debt issuance costs	-18.8	-1.7
Net cash provided by financing activities	693.4	128.1
Net Cash flows	-136.7	162.8
Effect of changes in foreign exchange rates on cash	-2.8	0.5
Net (decrease)/increase in cash and cash equivalents	-139.5	163.3
Cash and cash equivalents, beginning of year	297.4	91.3
Cash and cash equivalents, end of period	157.9	254.6
Supplemental disclosure of non-cash investing and financing activities:
Cash paid for interest, net of capitalized interest	176.9	160.2
Cash paid for income taxes	12.7	2.7
Non-cash purchases of long-lived assets through capital leasing	6.2	5.6
Increase/(decrease) in accruals for purchases of property and equipment	$8.60	($12.10)

Business_and_Basis_of_Presenta

Business and Basis of Presentation	9 Months Ended
	Mar. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Business and Basis of Presentation	(1) BUSINESS AND BASIS OF PRESENTATION
	Business
	Zayo Group, LLC, a Delaware limited liability company, was formed on May 4, 2007, and is the operating parent company of a number of subsidiaries engaged in bandwidth infrastructure provision and services. Zayo Group, LLC and its subsidiaries are collectively referred to as “Zayo Group” or the “Company.” Headquartered in Boulder, Colorado, the Company operates bandwidth infrastructure assets, including fiber networks and datacenters, in the United States and Europe to offer:
	—	Physical infrastructure, including dark fiber, mobile infrastructure and colocation services.
	—	Cloud and Connectivity, previously referred to as Lit services, including wavelengths, Ethernet, IP, SONET and Cloud services.
	—	Other services, provided by Zayo Professional Services and Zayo France.
	Zayo Group is wholly owned by Zayo Group Holdings, Inc. (“Holdings” or “ZGH”).
	On October 22, 2014, Holdings completed an initial public offering (“IPO”) of shares of its common stock, which were listed on the New York Stock Exchange (“NYSE”) under the ticker symbol “ZAYO”. Prior to Holding’s IPO, ZGH was wholly owned by Communications Infrastructure Investments, LLC ("CII"). The Company’s fiscal year ends June 30 each year.  The fiscal year ended June 30, 2014 is referred to as “Fiscal 2014” and the fiscal year ending June 30, 2015 as “Fiscal 2015.”
	Basis of Presentation
	The accompanying condensed consolidated financial statements include all the accounts of the Company and its wholly-owned subsidiaries. All inter-company accounts and transactions have been eliminated in consolidation. The accompanying condensed consolidated financial statements and related notes are unaudited and have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial reporting and pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”) for quarterly reports on Form 10-Q, and do not include all of the note disclosures required by GAAP for complete financial statements. These condensed consolidated financial statements should, therefore, be read in conjunction with the consolidated financial statements and notes thereto for the year ended June 30, 2014 included in the Company’s Annual Report on Form 10-K filed with the SEC on September 29, 2014 (the “Annual Report”). In the opinion of management, all adjustments considered necessary for the fair presentation of financial position, results of operations and cash flows of the Company have been included herein. The results of operations for the three and nine-month periods ended March 31, 2015 are not necessarily indicative of the operating results for any future interim period or the full year.
	Unless otherwise noted, dollar amounts and disclosures throughout the notes to the condensed consolidated financial statements relate to the Company’s operating results and are presented in millions of dollars.
	Significant Accounting Policies
	There have been no changes to the Company’s significant accounting policies described in its Annual Report.
	Use of Estimates
	The preparation of the Company’s 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 and estimating the common unit and 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.
	Reclassification of Network Related Expenses and Zayo Professional Services
	The Company has historically included certain network related expenses associated with the operations, support and maintenance of its network assets and technical facilities, including compensation and related benefits and stock-based compensation expense associated with personnel involved in these activities, within the line item “Selling, general and administrative expenses” in its consolidated statement of operations. The Company has changed its presentation of these network related expenses to be included in operating costs in its consolidated statements of operations to differentiate costs attributed to generating revenue from selling, general and administrative expenses. This reclassification does not impact the Company’s previously reported total operating costs and expenses, operating income subtotal or net loss total for the periods presented. The following tables reflect the reclassification of network related expenses from “Selling, general and administrative expenses” to “Operating costs” for each of the quarters and annual periods for Fiscal 2014.
	The following table reflects the reclassification of network related expenses from “Selling, general and administrative expenses” to “Operating costs” and the impact of the transfer of ZPS into the Company for each of the quarters and annual periods in Fiscal 2014.
			Fiscal 2014 Quarter Ended												Year Ended
			30-Sep			31-Dec			31-Mar			30-Jun			30-Jun-14
	Operating costs, as originally stated		$	34.9		$	35		$	35.4		$	36.2		$	141.5
	Reclassification of network-related expenses			42.8			49			47.7			53.3			192.8
	Transfer of Zayo Professional Services			2			1.9			1.8			3.3			9
	Operating costs, as adjusted		$	79.7		$	85.9		$	84.9		$	92.8		$	343.3
	Selling, general and administrative expenses,		$	117.4		$	134.2		$	142.7		$	176.9		$	571.2
	as originally stated
	Reclassification of network-related expenses			(42.8	)		(48.9	)		(47.8	)		(53.3	)		(192.8	)
	Transfer of Zayo Professional Services			1.8			1.7			1.7			1			6.2
	Selling, general and administrative expenses,		$	76.4		$	87		$	96.6		$	124.6		$	384.6
	as adjusted
	See also Note 3 - Transfer of Zayo Professional Services.
	The interim and annual financial information for Fiscal 2014 have been adjusted accordingly in the Company’s condensed consolidated balance sheet and statements of operations. The effect of the transfer of ZPS into the Company on net income/(loss), other comprehensive income/(loss), and any related per-share amounts was immaterial for all prior periods presented herein.
	Recently Issued Accounting Pronouncements
	On April 7, 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2015-03, Simplifying the Presentation of Debt Issuance Costs, which requires debt issuance costs related to a recognized debt liability to be presented on the balance sheet as a direct deduction from the debt liability, similar to the presentation of debt discounts.  The ASU is effective for public business entities for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years.  Early application is permitted.  The ASU requires retrospective application to all prior periods presented in the financial statements.  The Company has elected not to early adopt ASU 2015-03.  If adopted during the period, debt issuance costs and long term debt as reflected on the Company’s condensed consolidated balance sheets would decrease $73.9 and $89.4 as of March 31, 2015 and June 30, 2014, respectively.
	On May 28, 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. The new standard is effective for the Company on or after July 1, 2017. Early application is not permitted. 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 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.  In April 2015, the FASB tentatively decided to defer for one year the effective date of ASU 2014-09. The FASB also tentatively decided to permit entities to early adopt the standard. The tentative decision will be exposed in an upcoming proposed ASU.

Acquisitions

Acquisitions	9 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Acquisitions	(2) ACQUISITIONS
	As of March 31, 2015 and since its formation, the Company has consummated 34 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 2015
	Neo Telecoms (“Neo”)
	On July 1, 2014, the Company acquired a 96% equity interest in Neo, a Paris-based bandwidth infrastructure company. The purchase agreement also includes a call option to acquire the remaining equity interest on or after December 31, 2015. The purchase consideration of €54.1 (or $73.9), net of cash acquired, was in consideration of acquiring 96% equity ownership in Neo and a call option to purchase the remaining 4% equity interest in Neo, and is subject to certain adjustments post-closing. The consideration consisted of cash and was paid with cash on hand from the proceeds of the Sixth Amendment to the Company’s term loan facility. €8.7 (or $11.9) of the purchase consideration is currently held in escrow pending the expiration of the indemnification adjustment period. The acquisition was considered an asset purchase for tax purposes.
	Colo Facilities Atlanta (“AtlantaNAP”)
	On July 1, 2014, the Company acquired 100% of the equity interest in AtlantaNAP, a datacenter and managed services provider in Atlanta, for cash consideration of $52.5. $5.3 of the purchase price is currently held in escrow pending the expiration of the indemnification adjustment period. The acquisition was considered an asset purchase for tax purposes.
	IdeaTek Systems, Inc. (“IdeaTek”)
	Effective January 1, 2015, the Company acquired all of the equity interest in IdeaTek. The purchase price, subject to certain post-closing adjustments, was $53.6 and was paid with cash on hand.  $3.2 of the purchase consideration is currently held in escrow pending the expiration of the indemnification adjustment period.  The acquisition was considered a stock purchase for tax purposes.
	The IdeaTek acquisition added 1,800 route miles to the Company’s network in Kansas, and includes a dense metro footprint in Wichita, Kansas. The network spans across Kansas and connects to approximately 600 cellular towers and over 100 additional buildings.
	Latisys Holdings, LLC (“Latisys”)
	On February 23, 2015, the Company acquired the operating units of Latisys, a colocation and infrastructure as a service (“Iaas”) provider for a price of $677.5, net of cash acquired.  The Latisys acquisition was funded with the proceeds of the New Notes Offering (as defined in Note 6 – Long-Term Debt). $31.4 of the purchase consideration is currently held in escrow pending the expiration of the indemnification adjustment period. The acquisition was considered a stock purchase for tax purposes.
	The Latisys acquisition added colocation and IaaS services through eight datacenters across five markets in Northern Virginia, Chicago, Denver, Orange County and London. The acquired datacenters currently total over 185,000 square feet of billable space and 33 megawatts of critical power.
	Acquisitions Completed During Fiscal 2014
	Corelink Data Centers, LLC (“Corelink”)
	On August 1, 2013, the Company entered into an asset purchase agreement to acquire Corelink. The transaction was consummated on the same date, at which time the Company acquired substantially all of the net assets of this business for consideration of approximately $1.9, comprised of 301,949 preferred units of CII with an estimated fair value of $1.6 and cash of $0.3 net of cash acquired. The acquisition was considered a stock purchase for tax purposes. The purchase price was paid with cash on hand.
	Access Communications, Inc. (“Access”)
	On October 1, 2013, the Company acquired 100% of the equity interest in Access, a Minnesota corporation, for cash consideration of $40.1, net of cash acquired, of which $4.0 is currently held in escrow pending the expiration of the indemnification adjustment period. The acquisition was considered a stock purchase for tax purposes. The purchase price was paid with cash on hand.
	FiberLink, LLC (“FiberLink”)
	On October 2, 2013, the Company acquired 100% of the equity interest in FiberLink, an Illinois limited liability company, for cash consideration of $43.1, which was primarily funded with available funds drawn on the Company’s revolving credit facility. The acquisition was considered an asset purchase for tax purposes.
	CoreXchange, Inc. (“CoreXchange”)
	On March 4, 2014, the Company acquired 100% of the equity interest in CoreXchange, a data center, bandwidth and managed services provider located in Dallas, Texas for consideration of $17.2. Through the transaction, the Company acquired one new data center operation located at 8600 Harry Hines Blvd. and secured additional square footage in its existing data center. The consideration was paid with cash on hand. $1.8 is currently held in escrow pending the expiration of the indemnification adjustment period. The acquisition was considered an asset purchase for tax purposes.
	Geo Networks Limited (“Geo”)
	On May 16, 2014, the Company acquired 100% of the equity interest in Ego Holdings Limited, a London-based dark fiber provider. The consideration consisted of cash of £174.3 (or $292.3), net of cash acquired, and was funded with a combination of cash on hand and available funds drawn on the Company’s revolving credit facility. In conjunction with the acquisition, the Company repaid Geo’s existing debt obligations to the note holders totaling £113.4 and £69.1 was paid to the shareholders. The acquisition 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 March 31, 2015, 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 property, plant and equipment, goodwill and intangible assets, deferred revenue and resulting deferred taxes related to its acquisitions of Geo, AtlantaNAP, Neo, IdeaTek and Latisys. All information presented with respect to certain working capital and non-working capital acquired assets and liabilities assumed as it relates to these acquisitions are preliminary and subject to revision pending the final fair value analysis. During the first quarter of Fiscal 2015, the Company finalized its fair value analysis and resulting purchase accounting for the Access and FiberLink acquisitions. During the third quarter of Fiscal 2015, the Company finalized its fair value analysis and resulting purchase accounting for the CoreXchange acquisition.
	The table below reflects the Company's preliminary estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2015 acquisitions:
		AtlantaNAP			Neo			IdeaTek			Latisys
	Acquisition date	1-Jul-14			1-Jul-14			1-Jan-15			23-Feb-15
	Cash	$	—		$	4.2		$	—		$	9.4
	Other current assets		0.2			10.5			0.8			18.8
	Property and equipment		7			28.1			32.8			220.6
	Deferred tax assets, net		0.1			—			—			—
	Intangibles		21			26.6			24			243.2
	Goodwill		25.6			23.7			29.8			279
	Other assets		—			8.9			0.1			5.8
	Total assets acquired		53.9			102			87.5			776.8
	Current liabilities		1.4			11.3			4.4			10.2
	Deferred revenue		—			3.7			25.2			3.2
	Deferred tax liability, net		—			5.7			4.3			76.5
	Other liabilities		—			3.2			—			—
	Total liabilities assumed		1.4			23.9			33.9			89.9
	Net assets acquired		52.5			78.1			53.6			686.9
	Less cash acquired		—			(4.2	)		—			(9.4	)
	Net consideration paid	$	52.5		$	73.9		$	53.6		$	677.5
	The table below reflects the Company's estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2014 acquisitions:
		Corelink			Access			FiberLink			CoreXchange			Geo
	Acquisition date	1-Aug-13			1-Oct-13			2-Oct-13			4-Mar-14			16-May-14
	Cash	$	0.1		$	1.2		$	—		$	—		$	13.7
	Other current assets		0.5			2.3			0.8			0.5			9.2
	Property and equipment		15.9			11.5			15.9			3.2			221.2
	Deferred tax assets, net		—			—			7.7			0.2			—
	Intangibles		0.2			18			19.3			11			61.2
	Goodwill		3			24			19.8			3.4			108.8
	Other assets		0.5			—			0.1			—			9.8
	Total assets acquired		20.2			57			63.6			18.3			423.9
	Current liabilities		0.7			1			1.3			0.5			30.9
	Deferred revenue		0.2			5.1			19.2			0.4			44.4
	Capital lease obligations		14.3			—			—			0.2			—
	Deferred tax liability, net		3			9.6			—			—			38.9
	Other liabilities		—			—			—			—			3.7
	Total liabilities assumed		18.2			15.7			20.5			1.1			117.9
	Net assets acquired		2			41.3			43.1			17.2			306
Less cash acquired		(0.1	)		(1.2	)		—			—			(13.7	)
Net consideration paid	$	1.9		$	40.1		$	43.1		$	17.2		$	292.3
The goodwill arising from the Company’s acquisitions results from synergies, anticipated incremental sales to the acquired company customer base, and economies-of-scale expected from the acquisitions. The Company has allocated the goodwill to the reporting units (in existence on the respective acquisition dates) that were expected to benefit from the acquired goodwill. The allocation was determined based on the excess of the estimated fair value of the reporting unit over the estimated fair value of the individual assets acquired and liabilities assumed that were assigned to the reporting units. Note 4 - Goodwill, discloses the preliminary and/or final allocation of the Company’s acquired goodwill to each of its reporting units.
In each of the Company’s Fiscal 2014 and Fiscal 2015 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. The fair value of the acquired customer relationships for each acquisition was determined as follows: Fiscal 2015 acquisitions - AtlantaNAP, $21.0; Neo, $26.0, IdeaTek, $24.0; Latisys - $243.2.  Fiscal 2014 acquisitions - Access, $18.0; FiberLink, $19.3; CoreXchange, $11.0; and Geo, $41.4. The Company has not yet finalized the valuation of acquired customer relationships for Geo, Neo, IdeaTek and Latisys. For Fiscal 2015, the Company estimated the useful life of the acquired customer relationships to be approximately 15 years for AtlantaNAP, 19 years for Neo, 19 years for IdeaTek and 15 years for Latisys. For Fiscal 2014, the Company estimated the useful life of the acquired customer relationships to be approximately 20 years for Access, 12 years for Geo, 12 years for CoreXchange, and 18 years for FiberLink.
Purchase Accounting Estimates Associated with Deferred Taxes
Based on the Company’s fair value assessment related to deferred tax assets acquired in the Geo and Latisys acquisitions, a value of $38.9 and $76.5, respectively, was assigned to the acquired net deferred tax liabilities.
The tax effect of temporary differences that give rise to significant portions of the net deferred tax liabilities are as follows:
	Geo
	16-May-14
Deferred income tax assets:
Net operating loss carry forwards	$	2.5
Deferred revenue		3.8
Total deferred income tax assets		6.3
Deferred income tax liabilities:
Property and equipment		(33.0	)
Intangible assets		(12.2	)
Total deferred income tax liabilities		(45.2	)
Net deferred income tax liabilities	$	(38.9	)
	Latisys
	23-Feb-15
Deferred income tax assets:
Net operating loss carry forwards	$	53.9
Deferred revenue		1.3
Other		0.7
Total deferred income tax assets		55.9
Deferred income tax liabilities:
Property and equipment		(48.3	)
Intangible assets		(84.1	)
Total deferred income tax liabilities		(132.4	)
Net deferred income tax liabilities	$	(76.5	)
Adjustments to Purchase Accounting Estimates Associated with Prior Year Acquisitions
Access, FiberLink and CoreXchange
During the first quarter of Fiscal 2015, the Company finalized its acquisition accounting for Access and FiberLink and its previously reported allocation of the purchase consideration associated with these acquisitions as a result of changes to the original fair value estimates of certain items acquired. These changes are the result of additional information obtained since June 30, 2014 that related to facts and circumstances that existed at the respective acquisition dates. Related to the Access acquisition, property, plant and equipment increased by $3.1, customer relationship intangible assets increased by $2.0, and deferred tax liabilities increased by $2.0 related to the Company's final valuation of non-working capital acquired assets and the related deferred tax impacts. Related to the FiberLink acquisition, property, plant and equipment increased by $9.9, customer relationship intangible assets increased by $2.1, and deferred tax assets increased by $0.7 related to the Company's final valuation of non-working capital acquired assets and the related deferred tax impacts. The Company has recast the previously reported consolidated balance sheet as of June 30, 2014 in connection with the finalization of acquisition accounting for these acquisitions. The Company did not recast the previously reported consolidated statement of operations for the year ended June 30, 2014 due to the immaterial effect of the related adjustments.
During the third quarter of Fiscal 2015, the Company finalized its acquisition accounting for CoreXchange and its previously reported allocations of the purchase consideration associated with this acquisition.  As a result of changes to the original fair value estimates the following adjustments were made: other current assets decreased by $0.4, property and equipment increased by $0.2, customer relationships increase by $0.9 and current liabilities decreased by $0.1.  The Company has not recast the previously reported consolidated balance sheet as of June 30, 2014 or the previously reported consolidated statement of operations for the year ended June 30, 2014 due to the immaterial effect of the related adjustments.
Fibergate Holdings, Inc. (“Fibergate”) Settlement
On August 31, 2012, the Company acquired 100% of the equity interest in Fibergate, a privately held corporation, for total consideration of $118.3.  $17.6 of the purchase price was held in escrow pending the expiration of the working capital and indemnification adjustment period. Prior to the expiration of the indemnification adjustment period, the Company filed an indemnification claim against the former owners of Fibergate.  During the three months ended December 31, 2014, the Company and the former owners of Fibergate entered into a settlement agreement and mutual release, which resulted in a refund of $2.5 of the purchase price.  The $2.5 proceeds are included as a reduction to selling, general and administrative expenses on the condensed consolidated statement of operations for the nine months ended March 31, 2015.
Geo
During the nine months ended March 31, 2015, the Company made various adjustments to its previously reported provisional allocations of the purchase consideration associated with the Geo acquisition as a result of changes to the original fair value estimates of certain items acquired. These changes are the result of additional information obtained since June 30, 2014 that related to facts and circumstances that existed at the respective acquisition dates. As a result of changes to the original fair value estimates the following adjustments were made: other current assets decreased by $1.9, property and equipment increased by $1.7, other assets decreased by $0.1, current liabilities increased by $8.7, deferred revenue increased by $3.6, deferred tax liabilities, net increased by $1.4 and other liabilities increased by $3.7.  The Company has not recast the previously reported consolidated balance sheet as of June 30, 2014 or the previously reported consolidated statement of operations for the year ended June 30, 2014 due to the immaterial effect of the related adjustments.
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 (including spin-offs), 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 $1.5 and $6.0 during the three and nine months ended March 31, 2015, respectively, and nil and $0.8 during the three and nine months ended March 31, 2014, respectively. Transaction costs have been included in selling, general and administrative expenses in the condensed consolidated statements of operations and in cash flows from operating activities in the condensed consolidated statements of cash flows during these periods.
Pro-forma Financial Information
The pro forma results presented below include the effects of the Company’s Fiscal 2014 acquisitions of Corelink, Access, FiberLink, CoreXchange, and Geo and Fiscal 2015 acquisitions of the AtlantaNAP, Neo, IdeaTek and Latisys as if the acquisitions occurred on July 1, 2013. The pro forma net loss for the periods ended March 31, 2015 and 2014 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 2014 and 2015 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 below 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, 2013.
	Three months ended						Nine months ended
	March 31,						March 31,
	2015			2014			2015			2014
Revenue	$	357.4		$	333.3		$	1,057.90		$	986.8
Net loss	$	(61.0	)	$	(56.7	)	$	(187.0	)	$	(145.0	)
The Company is unable to determine the amount of revenue and net income associated with each acquisition recognized in the post-acquisition period as a result of integration activities.

Transfer_of_Zayo_Professional_

Transfer of Zayo Professional Services	9 Months Ended
	Mar. 31, 2015
Discontinued Operations And Disposal Groups [Abstract]
Transfer of Zayo Professional Services	(3) TRANSFER OF ZAYO PROFESSIONAL SERVICES
	On July 1, 2014, Zayo Professional Services ("ZPS"), a professional services business that provides network management and technical resources to customers, was transferred from Holdings to the Company. All of the assets and liabilities of ZPS were transferred to the Company as of July 1, 2014 and the transaction was accounted for as an equity transaction at carryover basis, as it was considered to be between entities under common control. The historical results of the Company, including the consolidated financial statements and footnotes, have been recast to include ZPS's historical financial results for all periods presented herein. See Note 1 - Business and Basis of Presentation - Reclassification of Network Related Expenses and Zayo Professional Services.

Goodwill

Goodwill	9 Months Ended
	Mar. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill	(4) GOODWILL
	The Company’s goodwill balance was $1,194.2 and $845.3 as of March 31, 2015 and June 30, 2014, respectively. Additions to goodwill during the nine months ended March 31, 2015 relate to the acquisitions of AtlantaNAP, Neo, IdeaTek and Latisys (see Note 2 - Acquisitions).
	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"), Cloud Services (“Cloud”) and Other (includes ZPS and Zayo France). The following roll forward reflects the allocation of goodwill acquired in the Company’s Fiscal 2014 and 2015 acquisitions to the Company’s reporting units:
	Product Group	As of		Fiscal 2015 acquisitions		Adjustments to Fiscal 2014 acquisitions			Foreign currency translation			As of
		30-Jun-14										31-Mar-15
	Dark Fiber	$	269.9	$	0.8	$	15.3		$	(10.2	)	$	275.8
	Waves		270		—		(0.1	)		(7.6	)		262.3
	Sonet		50.3		—		—			—			50.3
	Ethernet		96.7		4.5		—			(0.2	)		101
	IP		80.4		1.9		—			(0.3	)		82
	MIG		43.7		22.3		—			—			66
	zColo		19.6		252.4		(1.1	)		(0.1	)		270.8
	Cloud		—		52.5		—			—			52.5
	Other		14.7		23.7		—			(4.9	)		33.5
	Total	$	845.3	$	358.1	$	14.1		$	(23.3	)	$	1,194.20
	During the nine months ended March 31, 2015, goodwill decreased by $23.3 due to foreign currency movements impacting goodwill allocated to the U.K. and France operations.
	In addition, the Company has recast goodwill reported in the consolidated balance sheet as of June 30, 2014 in connection with the Company’s final valuation of property, plant and equipment and intangible assets and associated deferred taxes impact for the Access and FiberLink acquisitions, which resulted in a net decrease to goodwill of $15.8 (see Note 2 - Acquisitions).
	Previously reported provisional allocations of goodwill to the Waves and Dark Fiber reporting units have been adjusted as of June 30, 2014 in relation to the Geo acquisition, with a corresponding increase in goodwill allocated to the Waves SPG of $27.5 and an offsetting decrease in goodwill allocated to the Dark Fiber reporting unit.

Intangible_Assets

Intangible Assets	9 Months Ended
	Mar. 31, 2015
Intangible Assets Net Excluding Goodwill [Abstract]
Intangible Assets	(5) INTANGIBLE ASSETS
	Identifiable acquisition-related intangible assets as of March 31, 2015 and June 30, 2014 were as follows:
		Gross		Accumulated			Net
		Carrying		Amortization
		Amount
	31-Mar-15
	Finite-Lived Intangible Assets
	Customer relationships	$	1,085.00	$	(138.2	)	$	946.8
	Trade names		0.3		(0.1	)		0.2
	Underlying rights		2.2		(0.3	)		1.9
	Total		1,087.50		(138.6	)		948.9
	Indefinite-Lived Intangible Assets
	Certifications		3.5		—			3.5
	Underlying Rights		16.9		—			16.9
	Total	$	1,107.90	$	(138.6	)	$	969.3
	30-Jun-14
	Finite-Lived Intangible Assets
	Customer relationships	$	789.2	$	(104.2	)	$	685
	Trade names		0.1		—			0.1
	Underlying rights		1.8		(0.1	)		1.7
	Total		791.1		(104.3	)		686.8
	Indefinite-Lived Intangible Assets
	Certifications		3.5		—			3.5
	Underlying rights		19.4		—			19.4
	Total	$	814	$	(104.3	)	$	709.7

LongTerm_Debt

Long-Term Debt	9 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Long-Term Debt	(6) LONG-TERM DEBT
	As of March 31, 2015 and June 30, 2014, long-term debt was as follows:
		March 31,			June 30,
		2015			2014
	Term Loan Facility due 2019	$	1,995.50		$	2,010.80
	8.125% Senior Secured Notes due 2020		—			750
	10.125% Senior Unsecured Notes due 2020		325.6			500
	6.00% Senior Unsecured Notes due 2023		1,430.00		—
	Total debt obligations		3,751.10			3,260.80
	Unamortized discount on Term Loan Facility due		(17.8	)		(20.6	)
	2019
	Unamortized premium on 6.00% Senior Unsecured		7.3			—
	Notes due 2023
	Carrying value of debt		3,740.60			3,240.20
	Less current portion		(20.5	)		(20.5	)
	Long-term debt, less current portion	$	3,720.10		$	3,219.70
	On July 2, 2012, the Company and Zayo Capital, Inc. (“Zayo Capital”) issued $750.0 aggregate principal amount of 8.125% senior secured first-priority notes due 2020 (the “Senior Secured Notes”) and $500.0 aggregate principal amount of 10.125% senior unsecured notes due 2020 (the “Senior Unsecured Notes”, and together with the Senior Secured Notes, the “Existing Notes”). On July 2, 2012, the Company also entered into a $250.0 senior secured revolving credit facility (the “Revolver”) and a senior secured term loan facility (the “Term Loan Facility”), both of which have been subsequently amended (the “Credit Agreement”). The Term Loan Facility was issued at a discount of $30.0 and has a maturity date of July 2019. The issue discount is being amortized to interest expense over the term of the loan. The terms of the amended Term Loan Facility require the Company to make quarterly principal payments of $5.1 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 nine months ended March 31, 2015 and 2014, respectively).
	On November 26, 2013, the Company and Zayo Capital entered into a Fifth Amendment (the “Fifth Amendment”) to the Company’s Credit Agreement. Under the terms of the Fifth Amendment, the Term Loan Facility was increased by $150.0 to $1,749.8, and the interest rate was adjusted to LIBOR plus 3.0% with a minimum LIBOR rate of 1.0%. The amended terms represented a downward adjustment of 50 basis points on the interest rate from the Fourth Amendment (the “Fourth Amendment”) to the Credit Agreement. The interest rate on the Revolver was amended to LIBOR plus 2.75% (based on the Company’s current leverage ratio), which represented a downward adjustment of 25 basis points on the interest rate from the Fourth Amendment. In connection with the Fifth Amendment, the Company did not incur a re-pricing premium.  Interest rates on the Term Loan Facility and Revolver as of March 31, 2015 were 4.0% and 3.0%, respectively. Interest rates on the Term Loan Facility and Revolver as of June 30, 2014 were 4.0% and 3.0%, respectively.
	Also, in connection with the Fifth Amendment, the Company recognized an expense during the second quarter of Fiscal 2014 of $1.9 associated with debt extinguishment costs, including cash expense of $1.0 related to third party costs and non-cash expense of $0.9 associated with the write-off of the Company’s unamortized debt issuance costs and discount on the Term Loan Facility accounted for as an extinguishment. The Company also incurred an additional $1.5 in debt issuance costs in the second quarter of Fiscal 2014.
	On May 16, 2014, the Company and Zayo Capital entered into the Sixth Amendment to the Credit Agreement, which increased the Term Loan Facility by $275.0 to $2,015.9. The $275.0 add-on was priced at 99.5%, and the Company incurred debt issuance costs of $3.2. No other terms of the Credit Agreement were amended.
	On December 15, 2014 (the “Redemption Date”), the Company redeemed $75.0 of its outstanding 8.125% Senior Secured Notes at a price of 108% of the principal amount and $174.4 of its outstanding 10.125% Senior Unsecured Notes at a price of 110% (collectively, the “Note Redemption”). As part of the Note Redemption, the Company recorded an early redemption call premium of $23.8, which has been recorded as a loss on extinguishment of debt on the consolidated statements of operations for the nine months ended March 31, 2015.
	On January 23, 2015, the Company completed a private offering (the “January Notes Offering”) of $700.0 aggregate principal amount of senior unsecured notes due in 2023.  On March 9, 2015, the Company completed a $730.0 aggregate principal add on to the January Notes Offering at a premium of 1% (the “March Notes Offering”, and together with the January Notes Offering, the “2023 Notes”) resulting in aggregate proceeds for the 2023 Notes of $1,437.3.  The issue premium of $7.3 on the March Notes Offering is being accreted against interest expense over the term of the notes under the effective interest method.  The 2023 Notes bear interest at the rate of 6.00% per year, which is payable on April 1 and October 1 of each year, beginning on October 1, 2015. The 2023 Notes will mature on April 1, 2023.  The net proceeds from the January Notes Offering were used to fund the purchase of the Latisys acquisition.   The net proceeds from the March Notes Offering were used to redeem the Company’s remaining $675.0 8.125% Senior Secured Notes due 2020 (the “Second Note Redemption”) at a price of 105.75%.
	At any time on or after April 1, 2018, the 2023 Notes may be redeemed, in whole or in part, at the applicable redemption prices set forth in the indenture, plus accrued interest.  Before April 1, 2018, the 2023 Notes may be redeemed, in whole or in part, at a redemption price equal to 100% of their principal amount, plus accrued interest and a “make-whole” premium.  In addition, before April 1, 2018, up to 40% of the 2023 Notes may be redeemed at a redemption price equal to 106.00% of their principal amount, plus accrued interest, using the proceeds of certain equity offerings.
	The 2023 Notes will be fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by all of the Company’s current and future domestic restricted subsidiaries and any other restricted subsidiaries of the Company that guarantee any indebtedness of the Company or any guarantor.
	As part of the Second Note Redemption, the Company recorded an early redemption call premium of $38.8 which has been recorded as a loss on extinguishment of debt on the consolidated statements of operations for the three and nine months ended March 31, 2015.
	As of March 31, 2015, no amounts were outstanding under the Revolver. Standby letters of credit were outstanding in the amount of $9.2 as of March 31, 2015, leaving $240.8 available under the Revolver as of March 31, 2015. The Revolver is subject to a commitment fee of 0.5% of the weighted-average unused capacity and 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 the Company’s leverage ratio. The Revolver has a maturity date of July 2017.
	Debt covenants
	The Credit Agreement, as amended, contains a covenant that requires the Company to maintain a minimum fixed-charge coverage ratio.
	Pursuant to the Credit Agreement, the Company shall not permit its Fixed Charge Coverage Ratio, which is defined in the Credit Agreement as the ratio of the Company's annualized modified EBITDA (as defined in the Credit Agreement) during the most recent quarter minus Capital Expenditures (as defined in the Credit Agreement) for the twelve month period ended as of the end of each applicable fiscal quarter to interest expense for that same period, to be less than the minimum ratio for the applicable period set forth below:
	Fiscal Quarters Ending	Minimum
		Ratio
	September 30, 2014, December 31, 2014 and March 31, 2015	2.00 to 1.0
	June 30, 2015, September 30, 2015 and December 31, 2015	2.25 to 1.0
	March 31, 2016, June 30, 2016 and September 30, 2016	2.50 to 1.0
	December 31, 2016 and for each fiscal quarter thereafter	2.75 to 1.0
	The Company was in compliance with all covenants associated with its debt agreements as of March 31, 2015.
	The indentures governing the Existing Notes and 2023 Notes contain covenants that, among other things, restrict the ability of the Company 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 the Company’s restricted subsidiaries to pay dividends or make other payments to the Company, 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.
	Debt issuance costs
	In connection with the Existing Notes offering and 2023 Notes offerings, Revolver and Term Loan Facility and the subsequent amendments thereto, the Company incurred debt issuance costs of $102.1 (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.
	In connection with the Note Redemption and Second Note Redemption, net unamortized debt issuance costs of $16.1 and $23.2 were recorded as part of the loss on extinguishment of debt during the three and nine months ended March 31, 2015, respectively.
	The balance of debt issuance costs as of March 31, 2015 and June 30, 2014 was $73.9 and $89.4, net of accumulated amortization of $28.2 and $25.4, 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 $3.6 and $11.1 during the three and nine months ended March 31, 2015, respectively and $3.5 and $10.3 during the three and nine months ended March 31, 2014, respectively.
	Interest rate derivatives
	On August 13, 2012, the Company entered into interest rate swap agreements with an aggregate notional value of $750.0 and a maturity date of June 30, 2017. There were no up-front fees for these agreements. The contract states that the Company pays a 1.67% fixed rate of interest for the term of the agreement, beginning June 30, 2013. The counterparties pay to the Company the greater of actual LIBOR or 1.25%. The Company entered into the 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 as an increase or decrease in interest expense in the consolidated statements of operations for the applicable period. During the three and nine months ended March 31, 2015, respectively, $2.3 and $1.8 was recorded as an increase in interest expense for the change in the fair value of the interest rate swaps.  During the three and nine months ended March 31, 2014, respectively, nil and $1.9 was recorded as an increase in interest expense for the change in the fair value of the interest rate swaps. The fair value of the interest rate swaps of $3.8 and $2.0 is included in “Other long term liabilities” in the Company’s consolidated balance sheet as of March 31, 2015 and June 30, 2014, respectively.
	During the three and nine months ended March 31, 2015, the Company made payments of $0.8 and $2.4, respectively, on the interest rate swaps.   During the three and nine months ended March 31, 2014, the Company made payments of $0.8 and $1.6, respectively, on the interest rate swaps.

Income_Taxes

Income Taxes	9 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	(7) INCOME TAXES
	The Company, a limited liability company, is taxed at the Holdings level.  All income tax balances resulting from the operations of Zayo Group, on a separate return basis, are reflected in these financial statements.
	The Company’s provision/(benefit) for income taxes is summarized as follows:
		Three months ended March 31,						Nine months ended March 31,
		2015			2014			2015			2014
	Current income taxes
	Federal	$	(1.7	)	$	—		$	1.4		$	—
	State		2.7			—			4.5			2.1
	Foreign		—			—			0.8			—
	Total		1		—				6.7			2.1
	Deferred income taxes
	Federal		(15.7	)		16.3			(14.7	)		29.3
	State		(5.2	)		(5.5	)		(6.4	)		(5.8	)
	Foreign		1.5			1.3			1.1			4.2
	Total		(19.4	)		12.1			(20.0	)		27.7
	Total (benefit)/provision for income taxes	$	(18.4	)	$	12.1		$	(13.3	)	$	29.8
	The United States and foreign components of net loss before income taxes for the three and nine months ended March 31, 2015 and 2014 are as follows:
		Three months ended March 31,						Nine months ended March 31,
		2015			2014			2015			2014
	United States	$	(76.9	)	$	(20.6	)	$	(169.1	)	$	(73.7	)
	Foreign		4.8			(10.9	)		(4.5	)		(3.6	)
	Total	$	(72.1	)	$	(31.5	)	$	(173.6	)	$	(77.3	)
	The Company’s effective income tax rate differs from what would be expected if the federal statutory rate were applied to earnings before income taxes primarily because of certain expenses that represent permanent differences between book and tax expenses and deductions, such as stock-based compensation expense associated with the CII common units, that are recorded as an expense for financial reporting purposes but are not deductible for tax purposes.
	Reconciliations 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 nine-month periods ended March 31, 2015 and 2014 are as follows:
		Three months ended March 31,						Nine months ended March 31,
		2015			2014			2015			2014
	Expected benefit at statutory rate	$	(25.3	)	$	(10.3	)	$	(60.9	)	$	(26.8	)
	Increase due to:
	Non-deductible stock-based compensation		8.8			23.4			51			62.9
	State income taxes (benefit)/provision, net of		(3.8	)		(0.9	)		(8.3	)		(3.7	)
	federal benefit
	Transaction costs not deductible for tax purposes		0.3			0.1			0.6			0.2
	Foreign tax rate differential		(0.1	)		1			0.7			(0.1	)
	Release of accrual for uncertain tax position		—			—			—			(2.6	)
	Other, net		1.7			(1.2	)		3.6			(0.1	)
	(Benefit)/provision for income taxes	$	(18.4	)	$	12.1		$	(13.3	)	$	29.8
	Each interim period, management estimates the annual effective tax rate and applies that rate to its reported year-to-date earnings. The tax expense or benefit related to items for which management is unable to make reliable estimates or that are significant, unusual, or extraordinary items that will be separately reported, or reported net of their related tax effect, are individually computed and are recognized in the interim period in which those items occur. In addition, the effect of changes in enacted tax laws, tax rates or tax status is recognized in the interim period in which the change occurs.
	The computation of the annual estimated effective tax rate at each interim period requires certain estimates and significant judgments, including but not limited to the expected operating income for the year, projections of the proportion of income earned and taxed in various jurisdictions, permanent differences, and the likelihood of realizing deferred tax assets generated in both the current year and prior years. The accounting estimates used to compute the interim provision for income taxes may change as new events occur, more experience is acquired, additional information is obtained, or the tax environment changes.

Equity

Equity	9 Months Ended
	Mar. 31, 2015
Stockholders Equity Note [Abstract]
Equity	(8) EQUITY
	Zayo Group was initially formed on May 4, 2007, and is a wholly-owned subsidiary of Holdings. Prior to October 16, 2014, Holdings was a wholly owned subsidiary of CII (See Note 1 – Business). CII was organized on November 6, 2006, and subsequently capitalized on May 7, 2007, with capital contributions from various institutional and founder investors. Cash, property, and service proceeds from the capitalization of CII were contributed to the Company, and the contributions are reflected in the Company’s member’s equity.
	During the nine months ended March 31, 2015 there was a deemed modification to the Company’s stock compensation arrangements with employees and directors.  The modification resulted in a reclassification of previously recorded stock-based compensation liability to member’s interest (see Note 9 – Stock-Based Compensation).
	During the nine months ended March 31, 2015, Holdings contributed $279.7 of the proceeds from its IPO to the Company.  The proceeds are reflected as in increase to member’s equity on the Company’s Statement of Member’s equity.

StockBased_Compensation

Stock-Based Compensation	9 Months Ended
	Mar. 31, 2015
Share Based Compensation [Abstract]
Stock-Based Compensation	(9) 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				Nine months ended
		March 31,				March 31,
	Included in:	2015		2014		2015		2014
	Operating costs	$	4.1	$	4.9	$	19.4	$	12.9
	Selling, general and administrative expenses		36.6		60.3		138.4		152.2
	Total stock-based compensation expense	$	40.7	$	65.2	$	157.8	$	165.1
	CII Common units	$	23.6	$	65.1	$	133.2	$	164.7
	CII Preferred units		0.1		0.1		0.3		0.4
	Part A restricted stock units		3.5		—		6.1		—
	Part B restricted stock units		13.5		—		18.2		—
	Total stock-based compensation expense	$	40.7	$	65.2	$	157.8	$	165.1
	As of March 31, 2015, there were 494,825 Part A RSUs outstanding and 935,318 Part B target RSUs outstanding
	CII Common Units
	Prior to ZGH’s IPO, the Company was given authorization by CII to award 625,000,000 of CII’s common units as profits interests to employees, directors, and affiliates of the Company.  The common units were historically considered to be stock-based compensation with terms that required the awards to be classified as liabilities due to cash settlement features. The vested portion of the awards was reported as a liability and the fair value was re-measured at each reporting date until the date of settlement, with a corresponding charge (or credit) to stock-based compensation expense.  In connection with the ZGH’s IPO and the related amendment to the CII operating agreement, there was a deemed modification to the stock compensation arrangements with the Company’s employees and directors. As a result, previously issued common units which were historically accounted for as liability awards, became classified as equity awards.  Prior to reclassifying the common unit liability to equity, the Company re-measured the fair value of the CII common units factoring in the change in fair value since September 30, 2014 and the change in fair value caused by the modification.  The fair value of these previously vested common units was estimated to be $490.2 on the modification date and this amount is reflected in the Company’s condensed consolidated statement of Member’s equity as an increase to additional-paid-in-capital during the nine months ended March 31, 2015.   The initial fair value of the unrecognized compensation expense associated with unvested CII common units was $124.1, which is being recognized ratably over the remaining vesting period of the Company’s outstanding common units through May 15, 2017.
	On October 9, 2014, the Company and CII’s board of managers approved a non-liquidating distribution by CII of shares of ZGH’s common stock held by CII to holders of CII vested common units. Employees and independent directors of the Company with vested CII common units received shares of ZGH’s common stock equal in value to the underlying value of their vested CII common units. The total number of shares of ZGH’s common stock that were distributed to CII common unit holders in connection with this non-liquidating distribution was 20,460,047 shares.
	Employees with unvested CII common units will continue to receive monthly distributions from CII of ZGH’s common stock as they vest under the original terms of the CII common unit grant agreements.  A total of 6,392,071 shares of ZGH’s common stock associated with unvested CII common units that will be distributed subsequent to the IPO date. In addition, CII may be required to distribute additional shares of ZGH’s common stock to CII common unit holders on a quarterly basis through June 30, 2016 based on ZGH’s stock price performance, subject to the existing vesting provisions of the CII common units. The shares to be distributed to the common unit holders are based on a pre-existing distribution mechanism, whose primary input is ZGH’s stock price at each subsequent measurement date.  Any remaining shares of common stock owned by CII will be distributed to the existing CII preferred unit holders.  The total number of shares of ZGH’s common stock that will be distributed to existing CII preferred or common unit holders subsequent to the IPO date is 10,294,867 shares.
	The valuation of the CII common units as of the IPO date was determined based on a Monte Carlo simulation.  The Monte Carlo valuation analysis attempts to approximate the probability of certain outcomes by running multiple trial runs, called simulations, using random variables to generate potential future stock prices. This valuation technique was used to estimate the fair value associated with future distributions of common stock to CII common unit holders. The Monte Carlo simulation first projects the number of shares to be distributed by CII to the common unit holders at each subsequent measurement date based on stock price projections under each simulation. Shares attributable to unvested CII common units are subject to the existing vesting provisions of the CII common unit awards.  The estimated future value of shares scheduled to be distributed by CII based on vesting provisions are calculated under each independent simulation. The present value of the number of shares of common stock to be distributed to common unit holders under each simulation is then computed, and the average of each simulation is the fair value of ZGH’s common shares to be distributed by CII to the common unit holders. This value was then adjusted for prior non-liquidating distributions made by the Company to derive a value for CII common units by class and on per unit basis. These values were used to calculate the fair value of outstanding CII common units as of the IPO date. Various inputs and assumptions were utilized in the valuation method, including forfeiture behavior, vesting provisions, holding restrictions, peer companies’ historical volatility, and an appropriate risk-free rate.
	During the three and nine months ended March 31, 2015, the Company recognized $23.6 and $133.2, respectively, of stock-based compensation expense related to vesting of CII common units. During the three and nine months ended March 31, 2014, the Company recognized $65.1 and $164.7, respectively, of stock-based compensation expense related to vesting of CII common units. As of March 31, 2015, the unrecognized compensation associated with unvested CII common units was $90.6 million.
	CII Preferred Units
	CII has issued preferred units of CII to certain of the Company’s executives and independent directors as compensation. The terms of these preferred unit awards require the Company to record the award as an equity award. The Company estimates the fair value of these equity awards on the grant date and recognizes the related expense over the vesting period of the awards. As these awards have been issued by CII to employees and directors of the Company as compensation, the related expense has been recorded by the Company in the accompanying consolidated statements of operations. The Company recognized stock-based compensation expense and a related increase to the Company’s member’s interest of $0.1 and $0.3 for the three and nine months ended March 31, 2015 and $0.1 and $0.4 for the three and nine months ended March 31, 2014, respectively, including compensation recorded for preferred units granted in earlier periods.
	Also in connection with the non-liquidating distribution by CII approved on October 9, 2014, the Company’s CEO and independent directors with vested CII preferred units received shares of ZGH’s common stock equal to the underlying value of their vested CII preferred units.  In connection with the IPO, 256,265 shares of ZGH’s common stock were distributed to the Company’s CEO and independent directors equal in value to their vested CII preferred units.
	Performance Incentive Compensation Plan (“PCIP”)
	During October 2014, the Company adopted the 2014 Performance Compensation Incentive Plan (“PCIP”).  The PCIP includes incentive cash compensation (ICC) 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 two components: Part A and Part B.
	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 ZGH’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 ZGH’s common stock.
	During the three and nine months ended March 31, 2015, the Company recognized $2.9 and $5.1, respectively, of compensation expense associated with the vested portion of the Part A awards. The March 31, 2015 quarterly award is recorded as a liability totaling $1.9 as of March 31, 2015, as the awards represent an obligation denominated in a fixed dollar amount to be settled in a variable number of shares during the quarter ending June 30, 2015. Upon the issuance of the RSUs, the liability is re-measured and then reclassified to member’s interest, 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 March 31, 2015, the remaining unrecognized compensation cost to be expensed over the remaining vesting period for Part A awards is $15.4.
	On September 17, 2014, the Company’s Compensation Committee approved a one-time grant of Part A RSUs in an amount equal to $2.8, or 144,737 RSUs, to Dan Caruso, the Company’s Chief Executive Officer. In connection with the grant, Mr. Caruso’s annual salary was reduced to seventeen thousand five hundred dollars from $0.4. The grant was made on November 5, 2014, and the RSUs vest in full on December 31, 2015. During the three and nine months ended March 31, 2015, the Company recognized $0.6 and $1.0 of stock-based compensation expense associated with this Part A RSU grant, with a corresponding adjustment to member’s interest as the award is equity classified. The remaining unrecognized compensation cost associated with this Part A RSU grant is $1.8.
	Part B
	Under Part B of the PCIP, participants, who include members of the Company’s senior management team, are awarded quarterly grants of RSUs. The number of the RSUs earned by the participants is based on ZGH’s stock price performance over a four fiscal quarter measurement period and vest, assuming continuous employment at the end of the measurement period. The existence of a vesting provision that is associated with the performance of ZGH’s stock price is a market condition, which affects the determination of the grant date fair value.  Upon vesting, RSUs convert to an equal number of shares of ZGH’s common stock.
	The table below reflects the total Part B RSUs granted during each period presented, the maximum eligible shares of ZGH’s stock that the respective Part B RSU grant could be converted to ZGH’s common stock and the grant date fair value per Part B RSU:
		During the three months ended
		March 31,		December 31,
		2015		2014
	Part B RSUs granted		359,658		575,660
	Maximum eligible shares of the Company's stock		1,381,086		2,210,534
	Grant date fair value per Part B RSU	$	24.36	$	63.12
	During the three and nine months ended March 31, 2015, the Company recognized stock-based compensation expense of $13.5 and $18.2, respectively, related to Part B awards.
	The grant date fair value of Part B RSU grants is estimated utilizing a Monte Carlo simulation.  This simulation estimates the ten-day average closing stock price ending on the vesting date, the stock price performance over the performance period, and the number of common shares to be issued at the vesting date. Various assumptions are utilized in the valuation method, including the target stock price performance ranges and respective share payout percentages, the Company’s historical stock price performance and volatility, peer companies’ historical volatility and an appropriate risk-free rate. The aggregate future value of the grant under each simulation is calculated using the estimated per share value of the common stock at the end of the vesting period multiplied by the number of common shares projected to be granted at the vesting date. The present value of the aggregate grant is then calculated under each of the simulations, resulting in a distribution of potential present values. The fair value of the grant is then calculated based on the average of the potential present values. The remaining unrecognized compensation cost associated with Part B RSU grants is $28.3 at March 31, 2015.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	(10) 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 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 March 31, 2015 and June 30, 2014 due to the short maturity of these instruments.
	The carrying value of the Company’s note obligations reflect the original amounts borrowed and was $1,755.6 and $1,250.0 as of March 31, 2015 and June 30, 2014, respectively. Based on market interest rates for debt of similar terms and average maturities, the fair value of the Company’s notes as of March 31, 2015 and June 30, 2014 was estimated to be $1,805.9 and $1,294.8, 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 obligations reflects the original amounts borrowed, net of the unamortized discount and was $1,977.7 and $1,990.2 as of March 31, 2015 and June 30, 2014, respectively. The 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 3.00%. Since management does not believe that the Company’s credit quality has changed significantly since the date when the amended Term Loan Facility was entered into on May 16, 2014, 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 of one percentage point above the 1.0% LIBOR floor would increase the Company’s annual interest expense by approximately $20.0 before considering the offsetting effects of the Company’s interest rate swaps.
	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 $2.3 and $1.8 were recorded as an increase to interest expense during the three and nine months ended March 31, 2015 and nil and $1.9 for the three and nine months ended March 31, 2014, respectively. A hypothetical increase in LIBOR rates of 100 basis points would increase the fair value of the interest rate swaps by approximately $9.8.
	Financial instruments measured at fair value on a recurring basis are summarized below:
		Level	March 31,		June 30,
			2015		2014
	Liabilities Recorded at Fair Value in the Financial
	Statements:
	Interest rate swap	Level 2	$	3.8	$	2
	Prior to the deemed modification of the Companys stock-based compensation arrangements (See Note 9 – Stock-based Compensation), the Company recorded its stock based compensation liability at fair value.  The fair value of the Company’s stock-based compensation liability as of June 30, 2014 was $392.4.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Mar. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Commitments And Contingencies	(11) COMMITMENTS AND CONTINGENCIES
	Purchase Commitments
	At March 31, 2015, the Company was contractually committed for $165.5 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.
	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	9 Months Ended
	Mar. 31, 2015
Related Party Transaction Due From To Related Party [Abstract]
Related Party Transactions	(12) RELATED PARTY TRANSACTIONS
	The Company has ongoing contractual relationships with Onvoy, LLC and its subsidiaries (“OVS”). OVS is wholly owned by CII and provides voice and managed services  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 we recorded with OVS for the periods presented:
		Three months ended					Nine months ended
		March 31,					March 31,
		2015			2014		2015			2014
	Revenues	$	1.8		$	1.8	$	5.2		$	5.2
	Operating costs	$	(0.1	)	$	-0.3	$	(0.8	)	$	-1.1
	As of March 31, 2015 and June 30, 2014, the Company had a balance due from OVS in the amount of $0.2 and $0.1, respectively.
	As of December 31, 2014 and June 30, 2014, the Company had a balance due from Holdings in the amount of $10.1 and $0.8, respectively, related to costs paid by the Company in connection with Holdings’ initial public offering completed on October 22, 2014 (See Note 1 – Business).
	Dan Caruso, the Company’s Chief Executive Officer and Chairman of the Board of Directors, 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 quarterly and annual maximum reimbursement thresholds approved by the Company’s Nominating and Governance Committee. During the three and nine months ended March 31, 2015, the Company reimbursed Mr. Caruso $0.1 and $0.7, respectively, for his business use of the aircraft.

Segment_Reporting

Segment Reporting	9 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segment Reporting	(13) SEGMENT REPORTING
	The Company’s chief operating decision maker (“CODM”) is its Chief Executive Officer.
	The Company’s individual strategic product groups (“SPGs”) are organized into three reportable segments based on the similarities of business activities: Physical Infrastructure, Cloud and Connectivity and Other. The Physical Infrastructure reporting segment is comprised of the following SPGs: Dark Fiber, Mobile Infrastructure, and Zayo Colocation (“zColo”). The Cloud and Connectivity reporting segment is comprised of the following SPGs: Wavelengths, Ethernet, IP, SONET and Cloud. SPGs report directly to the segment managers who are responsible for the operations and financial results for the Physical Infrastructure, Cloud and Connectivity and Other reportable segments. The segment managers for each of the Physical Infrastructure, Cloud and Connectivity and Other reportable segments report directly to the CODM, and it is the financial results of those segments that are evaluated and drive the resource allocation decisions.
	The Company’s three reportable segments are described below:
	Physical Infrastructure. Through the Physical Infrastructure segment, the Company provides raw bandwidth infrastructure to customers that require more control of their internal networks. These services include dark fiber, mobile infrastructure (fiber-to-the-tower and small cell), and colocation and interconnection. 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. The Company’s datacenters offer colocation and interconnection services to its customers, who then house and power the Company’s computing and networking equipment for the purpose of aggregating and distributing data, voice, Internet, and video traffic. Physical Infrastructure 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 Physical Infrastructure segment generally tend to range from three to twenty years.
	Cloud and Connectivity. The Cloud and 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, SONET, and cloud services with capacity ranging from 1.54Mb to 100G. The Company targets customers who require a minimum of 10G of bandwidth across their networks. Cloud and 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.
	Other. The Other segment is primarily comprised of ZPS and Zayo France. ZPS provides network and technical resources to customers in designing, acquiring and maintaining their 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). Zayo France provides services using the Company's Paris and regional fiber network and nine colocation centers across France.
	Revenues for all of the Company’s products are included in one of the Company’s three reportable segments. The results of operations for each reportable 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 and rational. 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 from continuing 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 March 31, 2015
			Physical			Cloud and Connectivity			Other		Corp/		Total
			Infrastructure								elimination
	Revenue from external customers		$	164.3		$	163		$	13.4	$	—	$	340.7
	Segment Adjusted EBITDA		$	109.1		$	86.2		$	3.7	$	—	$	199
	Total assets		$	3,598.20		$	1,959.40		$	121.1	$	281.4	$	5,960.10
	Capital expenditures		$	82.2		$	46.7		$	1.2	$	—	$	130.1
			As of and for the nine months ended March 31, 2015
			Physical			Cloud and Connectivity			Other		Corp/		Total
			Infrastructure								elimination
	Revenue from external customers		$	466.7		$	476.5		$	42	$	—	$	985.2
	Segment Adjusted EBITDA		$	308.5		$	252.6		$	10.6	$	—	$	571.7
	Capital expenditures		$	226.8		$	145.3		$	2.8	$	—	$	374.9
			As of and for the three months ended March 31, 2014
			Physical			Cloud and Connectivity			Other		Corp/		Total
			Infrastructure								elimination
	Revenue from external customers		$	125		$	151.7		$	6.5	$	—	$	283.2
	Segment Adjusted EBITDA		$	82.4		$	82.6		$	1.9	$	—	$	166.9
	Capital expenditures		$	57.1		$	33.8		$	—	$	—	$	90.9
			As of and for the nine months ended March 31, 2014
			Physical			Cloud and Connectivity			Other		Corp/		Total
			Infrastructure								elimination
	Revenue from external customers		$	359.5		$	452.4		$	19.7	$	—	$	831.6
	Segment Adjusted EBITDA		$	237.1		$	244.7		$	5.6	$	—	$	487.4
	Capital expenditures		$	149		$	116.9		$	—	$	—	$	265.9
	Reconciliation from Segment Adjusted EBITDA to net earnings/(loss) from continuing operations
			Three months ended March 31,
			2015			2014
	Segment Adjusted EBITDA		$	199		$	166.9
	Interest expense			(60.7	)		(49.1	)
	Benefit/(provision) for income taxes			18.4			(12.1	)
	Depreciation and amortization expense			(100.1	)		(84.2	)
	Transaction costs			(1.5	)		—
	Stock-based compensation			(40.7	)		(65.2	)
	Loss on extinguishment of debt			(54.9	)		—
	Foreign currency (loss)/ gain on intercompany loans			(13.2	)		0.1
	Net loss from continuing operations		$	(53.7	)	$	(43.6	)
			Nine months ended March 31,
			2015			2014
	Segment Adjusted EBITDA		$	571.7		$	487.4
	Interest expense			(161.0	)		(150.9	)
	Benefit/(provision) for income taxes			13.3			(29.8	)
	Depreciation and amortization expense			(293.0	)		(246.9	)
	Transaction costs			(6.0	)		(0.8	)
	Stock-based compensation			(157.8	)		(165.1	)
	Loss on extinguishment of debt			(85.8	)		(1.9	)
Foreign currency (loss)/ gain on intercompany loans			(41.2	)		0.9
Non-cash loss on investments			(0.5	)		—
Net loss from continuing operations		$	(160.3	)	$	(107.1	)

Condensed_Consolidating_Financ

Condensed Consolidating Financial Information	9 Months Ended
	Mar. 31, 2015
Condensed Consolidating Financial Information [Abstract]
Condensed Consolidating Financial Information	(14) CONDENSED CONSOLIDATING FINANCIAL INFORMATION
	As discussed in Note 6 – Long-Term Debt, as of March 31, 2015, the Company has outstanding $325.6 Senior Unsecured Notes and $1,430.0 2023 Notes (collectively, our “Existing Notes”). The Existing Notes are fully and unconditionally guaranteed, jointly and severally, on an senior unsecured basis by all of the Company’s current and future domestic restricted subsidiaries. Zayo Capital does not have independent assets or operations. The non-guarantor subsidiaries consist of the foreign subsidiaries that were acquired in conjunction with the Company's acquisitions.
	The accompanying condensed consolidating financial information has been prepared and is presented to display the components of the Company’s balance sheets, statements of operations and statements of cash flows in a manner that allows an existing or future holder of the Company’s Existing Notes to review and analyze the current financial position and recent operating results of the legal subsidiaries that guarantee the Company’s debt obligations.
	The operating activities of the separate legal entities included in the Company’s consolidated financial statements are interdependent. The accompanying condensed consolidating financial information presents the results of operations, financial position and cash flows of each legal entity. Zayo Group and its guarantors provide services to each other during the normal course of business. These transactions are eliminated in the consolidated results of operations of the Company. Activity related to income taxes is included at the issuer, or Zayo Group level, and the Company's non-guarantor subsidiaries and is not allocated to the Company's guarantor subsidiaries in the condensed consolidated financial information presented below.
	Condensed Consolidating Balance Sheets (Unaudited)
	31-Mar-15
		Zayo Group, LLC			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Total
		(Issuer)
	Assets
	Current assets
	Cash and cash equivalents	$	127		$	5.7		$	25.2		$	—		$	157.9
	Trade receivables, net of allowance		50			15.4			29.1		—				94.5
	Due from related parties		10.3		—				1.4			(1.4	)		10.3
	Prepaid expenses		24.6			4.8			6.8		—				36.2
	Deferred income taxes, net		159.7		—				1.3		—				161
	Other assets		4.2			0.3			0.4		—				4.9
	Total current assets		375.8			26.2			64.2			(1.4	)		464.8
	Property and equipment, net		2,557.80			322.5			318.9		—				3,199.20
	Intangible assets, net		633.5			236			99.8		—				969.3
	Goodwill		749.9			283.9			160.4		—				1,194.20
	Debt issuance costs, net		73.9			—		—			—				73.9
	Other assets		35.3			8.9			14.5		—				58.7
	Related party receivable		284.3		—			—				(284.3	)	—
	Investment in subsidiary		491.3		—			—				(491.3	)	—
	Total assets	$	5,201.80		$	877.5		$	657.8		$	(777.0	)	$	5,960.10
	Liabilities and member's equity
	Current liabilities
	Current portion of long-term debt	$	20.5		$	—		$	—		$	—		$	20.5
	Accounts payable		24.3			3.6			6.9		—				34.8
	Accrued liabilities		124.1			14.1			43.1		—				181.3
	Due to related parties		—			1.4		—				(1.4	)	—
	Accrued interest		24.2			—		—			—				24.2
	Capital lease obligations, current		2			1.5			0.5		—				4
	Deferred revenue, current		71.1			2.8			14.6		—				88.5
	Total current liabilities		266.2			23.4			65.1			(1.4	)		353.3
	Long-term debt, non-current		3,720.10			—		—			—				3,720.10
	Related party debt, long-term	—			—				284.3			(284.3	)		—
	Capital lease obligation, non-current		5.6			19			3.9		—				28.5
	Deferred revenue, non-current		548.4			4.8			35.7		—				588.9
	Stock-based compensation liability		1.5			0.1			0.3		—				1.9
	Deferred income taxes, net		167.3			—			46.1		—				213.4
	Other long-term liabilities		13.4			10.3			2.5		—				26.2
	Total liabilities		4,722.50			57.6			437.9			(285.7	)		4,932.30
	Member's equity
	Member's interest		1,554.70			236.9			250.9			(491.3	)		1,551.20
	Accumulated other comprehensive (loss)/income		0.9		—				(22.0	)	—				(21.1	)
	Accumulated deficit		(527.8	)		34.5			(9.0	)		—			(502.3	)
	Total member's equity		1,027.80			271.4			219.9			(491.3	)		1,027.80
	Total liabilities and member's equity	$	5,750.30		$	329		$	657.8		$	(777.0	)	$	5,960.10
	Condensed Consolidating Balance Sheets (Unaudited)
	30-Jun-14
		Zayo Group,			Guarantor			Non-			Eliminations			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
		(Issuer)
	Assets
	Current assets
	Cash and cash equivalents	$	260.8		$	1			35.6		$	—		$	297.4
	Trade receivables, net		37.5			6			15.5			—			59
	Due from related parties		1.1			—			0.6			(0.8	)		0.9
	Prepaid expenses		18.9			1.4			5.3			—			25.6
	Deferred income taxes		158.9			—			1.5			—			160.4
	Other assets, current		1.9			—			0.5			—			2.4
	Total current assets		479.1			8.4			59			(0.8	)		545.7
Property and equipment, net		2,402.40			95.2			323.8			—			2,821.40
Intangible assets, net		584.4			29.8			95.5			—			709.7
Goodwill		682.3			17.8			145.2			—			845.3
Debt issuance costs, net		89.4			—			—			—			89.4
Other assets		23.6			3.3			10.9			—			37.8
Related party receivable, long-term		267.8			—			—			(267.8	)		—
Investment in subsidiary		303.7			—			—			(303.7	)		—
Total assets	$	4,832.70		$	154.5		$	634.4		$	(572.3	)	$	5,049.30
Liabilities and member’s equity
Current liabilities
Current portion of long-term debt	$	20.5		$	—		$	—		$	—		$	20.5
Accounts payable		20.7			4.3			2			—			27
Accrued liabilities		126			7			26.6			—			159.6
Accrued interest		57.1			—			—			—			57.1
Capital lease obligations, current		1.5			0.9			—			—			2.4
Due to related-parties		—			—			0.8			(0.8	)		—
Deferred revenue, current		56.9			1.4			17.1			—			75.4
Total current liabilities		282.7			13.6			46.5			(0.8	)		342
Long-term debt, non-current		3,219.70			—			—			—			3,219.70
Related party debt, long-term		—			—			267.8			(267.8	)		—
Capital lease obligations, non-current		5.6			15.6			1.7			—			22.9
Stock-based compensation liability		459.5			4			33.4			—			496.9
Deferred income taxes, net		345			22.2			25.2			—			392.4
Deferred income taxes, net		106.5			—			45.3			—			151.8
Other long-term liabilities		12.4			9.8			0.1			—			22.3
Total liabilities		4,431.40			65.2			420			(268.6	)		4,648.00
Member’s equity
Member’s interest		778			49.6			205			(303.7	)		728.9
Accumulated other comprehensive loss		—			—			14.4			—			14.4
(Accumulated deficit)/retained earnings		(376.7	)		39.7			(5.0	)		—			(342.0	)
Total member’s equity		401.3			89.3			214.4			(303.7	)		401.3
Total liabilities and member’s equity	$	4,832.70		$	154.5		$	634.4		$	(572.3	)	$	5,049.30
Condensed Consolidating Statements of Operations (Unaudited)
For the three months ended March 31, 2015
	Zayo Group,			Guarantor			Non-			Eliminations			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
	(Issuer)
Revenue	$	264.1		$	38.3		$	38.3		$	—		$	340.7
Operating costs and expenses
Operating costs (excluding depreciation and		77.5			13.4			10			—			100.9
amortization)
Selling, general and administrative expenses		60.6			10.4			12			—			83
Depreciation and amortization		80.8			12.4			6.9			—			100.1
Total operating costs and expenses		218.9			36.2			28.9			—			284
Operating income		45.2			2.1			9.4			—			56.7
Other expenses
Interest expense		(56.5	)		—			(4.2	)		—			(60.7	)
Loss on extinguishment of debt		(53.8	)		(1.0	)		(0.1	)		—			(54.9	)
Foreign currency loss on intercompany loans		(13	)		—			(0.6	)					(13.2	)
Other expenses, net		—			—			—			—			—
Equity in net earnings of subsidiaries		4.4			—			—			(4.4	)		—
Total other expense, net		(118.5	)		(1.0	)		(4.9	)		(4.4	)		(128.8	)
(Loss)/earnings before provision for income taxes		(73.3	)		1.1			4.5			(4.4	)		(72.1	)
(Benefit)/provision for income taxes		(19.6	)		—			1.2			—			(18.4	)
Net (loss)/earnings	$	(53.7	)	$	1.1		$	3.3		$	(4.4	)	$	(53.7	)
Condensed Consolidating Statements of Operations (Unaudited)
For the nine months ended March 31, 2015
	Zayo Group,			Guarantor			Non-			Eliminations			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
	(Issuer)
Revenue	$	770.9		$	98.8		$	115.5		$	—		$	985.2
Operating costs and expenses
Operating costs (excluding depreciation and		236.5			36.2			33.3			—			306
amortization)
Selling, general and administrative expenses		206.3			25.5			39.9			—			271.7
Depreciation and amortization		238.4			23.2			31.4			—			293
Total operating costs and expenses		681.2			84.9			104.6			—			870.7
Operating income		89.7			13.9			10.9			—			114.5
Other expenses
Interest expense		(148.3	)		—			(12.7	)		—			(161.0	)
Loss on extinguishment of debt		(83.7	)		(1.5	)		(0.6	)		—			(85.8	)
Foreign currency loss on intercompany loans		(39.7	)		—			(1.5	)					(41.2	)
Other expenses, net		(0.1	)		—			—			—			(0.1	)
Equity in net earnings of subsidiaries		6.6			—			—			(6.6	)		—
Total other expense, net		(265.2	)		(1.5	)		(14.8	)		(6.6	)		(288.1	)
(Loss)/earnings before provision for income taxes		(175.5	)		12.4			(3.9	)		(6.6	)		(173.6	)
(Benefit)/provision for income taxes		(15.2	)		0.4			1.5			—			(13.3	)
Net (loss)/earnings	$	(160.3	)	$	12		$	(5.4	)	$	(6.6	)	$	(160.3	)
Condensed Consolidating Statements of Operations (Unaudited)
For the three months ended March 31, 2014
	Zayo Group,			Guarantor			Non-			Eliminations			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
	(Issuer)
Revenue	$	240.8		$	25.7		$	16.7		$	—		$	283.2
Operating costs and expenses
Operating costs (excluding depreciation and		70.2			11.1			3.6			—			84.9
amortization)
Selling, general and administrative expenses		68.1			8			20.5			—			96.6
Depreciation and amortization		77.1			3.5			3.6			—			84.2
Total operating costs and expenses		215.4			22.6			27.7			—			265.7
Operating income		25.4			3.1			(11.0	)		—			17.5
Other expenses
Interest expense		(49.0	)		—			(0.1	)		—			(49.1	)
Loss on extinguishment of debt		—			—			—			—			—
Foreign currency loss on intercompany loans		—			—			0.1						0.1
Other expenses, net		—			—			—			—			—
Equity in net earnings of subsidiaries		(10.1	)		—			—			10.1			—
Total other expense, net		(59.1	)		—			—			10.1			(49.0	)
(Loss)/earnings before provision for income taxes		(33.7	)		3.1			(11.0	)		10.1			(31.5	)
(Benefit)/provision for income taxes		9.9			0.8			1.4			—			12.1
Net (loss)/earnings	$	(43.6	)	$	2.3		$	(12.4	)	$	10.1		$	(43.6	)
Condensed Consolidating Statements of Operations (Unaudited)
For the Nine months ended March 31, 2014
	Zayo Group,			Guarantor			Non-			Eliminations			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
	(Issuer)
Revenue	$	711.6		$	73.1		$	46.9		$	—		$	831.6
Operating costs and expenses
Operating costs (excluding depreciation and		206.7			32.8			11			—			250.5
amortization)
Selling, general and administrative expenses		209.2			21			29.8			—			260
Depreciation and amortization		227.4			9.2			10.3			—			246.9
Total operating costs and expenses		643.3			63			51.1			—			757.4
Operating income		68.3			10.1			(4.2	)		—			74.2
Other expenses
Interest expense		(150.6	)		—			(0.3	)		—			(150.9	)
Loss on extinguishment of debt		(2.0	)		—			0.1			—			(1.9	)
Foreign currency loss on intercompany loans		—			—			0.9						0.9
Other expenses, net		0.4			—			—			—			0.4
Equity in net earnings of subsidiaries		0.3			—			—			(0.3	)		—
Total other expense, net		(151.9	)		—			0.7			(0.3	)		(151.5	)
(Loss)/earnings before provision for income taxes		(83.6	)		10.1			(3.5	)		(0.3	)		(77.3	)
(Benefit)/provision for income taxes		23.5			2.2			4.1			—			29.8
Net (loss)/earnings	$	(107.1	)	$	7.9		$	(7.6	)	$	(0.3	)	$	(107.1	)
Condensed Consolidating Statements of Cash Flows
Nine months ended March 31, 2015
	Zayo Group,			Guarantor			Non-			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
Net cash provided by operating activities	$	331			28			43.1		$	402.1
Cash flows from investing activities:
Purchases of property and equipment, net of stimulus grants		(318.8	)		(27.9	)		(28.2	)		(374.9	)
Acquisitions, net of cash acquired		(182.4	)		-601			(73.9	)		(857.3	)
Net cash used in investing activities		(501.2	)		(628.9	)		(102.1	)		(1,232.2	)
Cash flows from financing activities:
Proceeds from debt		1,437.30			—			—			1,437.30
Equity contributions		-332.9			606.7			5.9			279.7
Principal payments on long-term debt		(939.8	)		—			—			(939.8	)
Payment of early redemption fees on debt extinguished		(62.6	)		—			—			(62.6	)
Principal repayments on capital lease obligations		(1.1	)		(1.1	)		(0.2	)		(2.4	)
(Payment of)/receipt from intercompany loans		(40.4	)					40.4			—
Payment of debt issuance costs		(18.8	)		—			—			(18.8	)
Net cash provided by financing activities		41.7			605.6			46.1			693.4
Effect of changes in foreign exchange rates on cash		(5.3	)		—			2.5			(2.8	)
Net (decrease)/increase in cash and cash equivalents		(133.8	)		4.7			(10.4	)		(139.5	)
Cash and cash equivalents, beginning of period		260.8			1			35.6			297.4
Cash and cash equivalents, end of period	$	127			5.7			25.2		$	157.9
Condensed Consolidating Statements of Cash Flows
Nine months ended March 31, 2014
	Zayo Group,			Guarantor			Non-			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
Net cash provided by operating activities	$	356.1			21.8			23.7			401.6
Cash flows from investing activities:
Purchases of property and equipment, net of stimulus grants		(237.0	)		(18.0	)		(10.9	)		(265.9	)
Acquisitions, net of cash acquired		(81.3	)		(19.7	)		—			(101.0	)
Net cash used in investing activities		(318.3	)		(37.7	)		(10.9	)		(366.9	)
Cash flows from financing activities:
Proceeds from debt		195			—			—			195
Principal payments on long-term debt		(57.9	)		—			—			(57.9	)
Equity contributions		(21.4	)		21.4			—			—
Distribution to parent		(0.4	)		—			—			(0.4	)
Principal repayments on capital lease obligations		(1.4	)		(5.5	)		—			(6.9	)
Payment of debt issuance costs		(1.7	)		—			—			(1.7	)
Net cash provided by financing activities		112.2			15.9			—			128.1
Effect of changes in foreign exchange rates on cash		—			—			0.5			0.5
Net (decrease)/increase in cash and cash equivalents		150			(0.0	)		13.3			163.3
Cash and cash equivalents, beginning of period		86.8			1			3.5			91.3
Cash and cash equivalents, end of period	$	236.8		$	1		$	16.8		$	254.6

Subsequent_Events

Subsequent Events	9 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	(15) SUBSEQUENT EVENTS
	Seventh Amendment to Credit Agreement
	On April 17, 2015, the Company entered into a Seventh Amendment (the “Seventh Amendment”) to the Company’s Credit Agreement (as amended through the Seventh Amendment, the “Credit Agreement”) governing the Company’s Term Loan Facility and the Revolver (collectively with the Term Loan Facility, the “Credit Facilities”). Under the Seventh Amendment, the Revolver was increased from $250.0 to $450.0, and the maturity date of the Revolver was extended to the earliest of (i) five years after the effective date of the Seventh Amendment, (ii) six months prior to the maturity date of the Term Loan Facility, subject to repayment or refinancing thereof, and (iii) six months prior to the maturity date of the Company’s Senior Unsecured Notes, subject to repayment or refinancing thereof. The Seventh Amendment also increased the letter of credit commitment from $30.0 to $50.0 and removed the Fixed Charge Coverage Ratio maintenance requirement and replaced such covenant with a springing Senior Secured Leverage Ratio maintenance requirement that will come into effect if at any time the Term Loan Facility is amended or refinanced to remove all financial maintenance covenants. The springing Senior Secured Leverage Ratio restricts the Company’s Senior Secured Leverage Ratio from exceeding 5.25:1.00.
	Further, pursuant to the Seventh Amendment, up to $50.0 of revolving loans and letters of credit may be denominated in or issued in, as applicable, Euros or British Pound Sterling.
	Senior Notes Due 2025
	On May 6, 2015, the Company completed a private offering of $350.0 aggregate principal amount of senior unsecured notes (the “$350.0 Senior Unsecured Notes”).    The $350.0 Senior Unsecured Notes bear interest at the rate of 6.375% per year. Interest on the $350.0 Senior Unsecured Notes is payable on May 15 and November 15 of each year, beginning on November 15, 2015. The $350.0 Senior Unsecured Notes will mature on May 15, 2025.  The net proceeds from the $350.0 Senior Unsecured Notes were used to repay a portion of the Company’s Term Loan Facility.
	At any time on or after May 15, 2020, the $350.0 Senior Unsecured Notes may be redeemed, in whole or in part, at the redemption prices set forth below plus accrued and unpaid interest:
	Year	Redemption Price
	2020		103.19	%
	2021		102.13	%
	2022		101.06	%
	2023 and thereafter		100	%
	Before May 15, 2020 the $350.0 Senior Unsecured Notes may be redeemed, in whole or in part, at a redemption price equal to 100% of their principal amount, plus accrued interest and a “make-whole” premium.  In addition, before May 15, 2018, up to 40% of the 2025 Notes may be redeemed at a redemption price equal to 106.375% of their principal amount, plus accrued interest, using the proceeds of certain equity offerings.
	The $350.0 Senior Unsecured Notes will be fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by all of the Issuers’ current and future domestic restricted subsidiaries and any other restricted subsidiaries of the Issuers that guarantee any indebtedness of the Issuers or any guarantor.
	Amended and Restated Credit Agreement
	Concurrently with the $350.0 Senior Unsecured Notes offering, the Company entered into an amendment and restatement of its Credit Agreement (the “Amended and Restated Credit Agreement”). The Amended and Restated Credit Agreement extended the maturity of the Term Loan Facility to 2021, aligned certain covenants with the New 2023 Notes and added additional covenant flexibility.

Business_and_Basis_of_Presenta1

Business and Basis of Presentation (Policies)	9 Months Ended
	Mar. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Use of Estimates	Use of Estimates
	The preparation of the Company’s 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 and estimating the common unit and 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.
Reclassification of Network Related Expenses and Zayo Professional Services	Reclassification of Network Related Expenses and Zayo Professional Services
	The Company has historically included certain network related expenses associated with the operations, support and maintenance of its network assets and technical facilities, including compensation and related benefits and stock-based compensation expense associated with personnel involved in these activities, within the line item “Selling, general and administrative expenses” in its consolidated statement of operations. The Company has changed its presentation of these network related expenses to be included in operating costs in its consolidated statements of operations to differentiate costs attributed to generating revenue from selling, general and administrative expenses. This reclassification does not impact the Company’s previously reported total operating costs and expenses, operating income subtotal or net loss total for the periods presented. The following tables reflect the reclassification of network related expenses from “Selling, general and administrative expenses” to “Operating costs” for each of the quarters and annual periods for Fiscal 2014.
	The following table reflects the reclassification of network related expenses from “Selling, general and administrative expenses” to “Operating costs” and the impact of the transfer of ZPS into the Company for each of the quarters and annual periods in Fiscal 2014.
		Fiscal 2014 Quarter Ended												Year Ended
		30-Sep			31-Dec			31-Mar			30-Jun			30-Jun-14
	Operating costs, as originally stated	$	34.9		$	35		$	35.4		$	36.2		$	141.5
	Reclassification of network-related expenses		42.8			49			47.7			53.3			192.8
	Transfer of Zayo Professional Services		2			1.9			1.8			3.3			9
	Operating costs, as adjusted	$	79.7		$	85.9		$	84.9		$	92.8		$	343.3
	Selling, general and administrative expenses,	$	117.4		$	134.2		$	142.7		$	176.9		$	571.2
	as originally stated
	Reclassification of network-related expenses		(42.8	)		(48.9	)		(47.8	)		(53.3	)		(192.8	)
	Transfer of Zayo Professional Services		1.8			1.7			1.7			1			6.2
	Selling, general and administrative expenses,	$	76.4		$	87		$	96.6		$	124.6		$	384.6
	as adjusted
	See also Note 3 - Transfer of Zayo Professional Services.
	The interim and annual financial information for Fiscal 2014 have been adjusted accordingly in the Company’s condensed consolidated balance sheet and statements of operations. The effect of the transfer of ZPS into the Company on net income/(loss), other comprehensive income/(loss), and any related per-share amounts was immaterial for all prior periods presented herein.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements
	On April 7, 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) 2015-03, Simplifying the Presentation of Debt Issuance Costs, which requires debt issuance costs related to a recognized debt liability to be presented on the balance sheet as a direct deduction from the debt liability, similar to the presentation of debt discounts.  The ASU is effective for public business entities for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years.  Early application is permitted.  The ASU requires retrospective application to all prior periods presented in the financial statements.  The Company has elected not to early adopt ASU 2015-03.  If adopted during the period, debt issuance costs and long term debt as reflected on the Company’s condensed consolidated balance sheets would decrease $73.9 and $89.4 as of March 31, 2015 and June 30, 2014, respectively.
	On May 28, 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. The new standard is effective for the Company on or after July 1, 2017. Early application is not permitted. 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 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.  In April 2015, the FASB tentatively decided to defer for one year the effective date of ASU 2014-09. The FASB also tentatively decided to permit entities to early adopt the standard. The tentative decision will be exposed in an upcoming proposed ASU.

Business_and_Basis_of_Presenta2

Business and Basis of Presentation (Tables)	9 Months Ended
	Mar. 31, 2015
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Selling General and Administrative Expenses	The following table reflects the reclassification of network related expenses from “Selling, general and administrative expenses” to “Operating costs” and the impact of the transfer of ZPS into the Company for each of the quarters and annual periods in Fiscal 2014.
		Fiscal 2014 Quarter Ended												Year Ended
		30-Sep			31-Dec			31-Mar			30-Jun			30-Jun-14
	Operating costs, as originally stated	$	34.9		$	35		$	35.4		$	36.2		$	141.5
	Reclassification of network-related expenses		42.8			49			47.7			53.3			192.8
	Transfer of Zayo Professional Services		2			1.9			1.8			3.3			9
	Operating costs, as adjusted	$	79.7		$	85.9		$	84.9		$	92.8		$	343.3
	Selling, general and administrative expenses,	$	117.4		$	134.2		$	142.7		$	176.9		$	571.2
	as originally stated
	Reclassification of network-related expenses		(42.8	)		(48.9	)		(47.8	)		(53.3	)		(192.8	)
	Transfer of Zayo Professional Services		1.8			1.7			1.7			1			6.2
	Selling, general and administrative expenses,	$	76.4		$	87		$	96.6		$	124.6		$	384.6
	as adjusted

Acquisitions_Tables

Acquisitions (Tables)	9 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Schedule of Acquisitions	The table below reflects the Company's preliminary estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2015 acquisitions:
		AtlantaNAP			Neo			IdeaTek			Latisys
	Acquisition date	1-Jul-14			1-Jul-14			1-Jan-15			23-Feb-15
	Cash	$	—		$	4.2		$	—		$	9.4
	Other current assets		0.2			10.5			0.8			18.8
	Property and equipment		7			28.1			32.8			220.6
	Deferred tax assets, net		0.1			—			—			—
	Intangibles		21			26.6			24			243.2
	Goodwill		25.6			23.7			29.8			279
	Other assets		—			8.9			0.1			5.8
	Total assets acquired		53.9			102			87.5			776.8
	Current liabilities		1.4			11.3			4.4			10.2
	Deferred revenue		—			3.7			25.2			3.2
	Deferred tax liability, net		—			5.7			4.3			76.5
	Other liabilities		—			3.2			—			—
	Total liabilities assumed		1.4			23.9			33.9			89.9
	Net assets acquired		52.5			78.1			53.6			686.9
	Less cash acquired		—			(4.2	)		—			(9.4	)
	Net consideration paid	$	52.5		$	73.9		$	53.6		$	677.5
	The table below reflects the Company's estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2014 acquisitions:
		Corelink			Access			FiberLink			CoreXchange			Geo
	Acquisition date	1-Aug-13			1-Oct-13			2-Oct-13			4-Mar-14			16-May-14
	Cash	$	0.1		$	1.2		$	—		$	—		$	13.7
	Other current assets		0.5			2.3			0.8			0.5			9.2
	Property and equipment		15.9			11.5			15.9			3.2			221.2
	Deferred tax assets, net		—			—			7.7			0.2			—
	Intangibles		0.2			18			19.3			11			61.2
	Goodwill		3			24			19.8			3.4			108.8
	Other assets		0.5			—			0.1			—			9.8
	Total assets acquired		20.2			57			63.6			18.3			423.9
	Current liabilities		0.7			1			1.3			0.5			30.9
	Deferred revenue		0.2			5.1			19.2			0.4			44.4
	Capital lease obligations		14.3			—			—			0.2			—
	Deferred tax liability, net		3			9.6			—			—			38.9
	Other liabilities		—			—			—			—			3.7
	Total liabilities assumed		18.2			15.7			20.5			1.1			117.9
	Net assets acquired		2			41.3			43.1			17.2			306
	Less cash acquired		(0.1	)		(1.2	)		—			—			(13.7	)
	Net consideration paid	$	1.9		$	40.1		$	43.1		$	17.2		$	292.3
Schedule of Deferred Tax Assets and Liabilities	The tax effect of temporary differences that give rise to significant portions of the net deferred tax liabilities are as follows:
		Geo
		16-May-14
	Deferred income tax assets:
	Net operating loss carry forwards	$	2.5
	Deferred revenue		3.8
	Total deferred income tax assets		6.3
	Deferred income tax liabilities:
	Property and equipment		(33.0	)
	Intangible assets		(12.2	)
	Total deferred income tax liabilities		(45.2	)
	Net deferred income tax liabilities	$	(38.9	)
		Latisys
		23-Feb-15
	Deferred income tax assets:
	Net operating loss carry forwards	$	53.9
	Deferred revenue		1.3
	Other		0.7
	Total deferred income tax assets		55.9
	Deferred income tax liabilities:
	Property and equipment		(48.3	)
	Intangible assets		(84.1	)
	Total deferred income tax liabilities		(132.4	)
	Net deferred income tax liabilities	$	(76.5	)
Schedule Of Pro-Forma Financial Information (Unaudited)	The unaudited pro forma financial information below 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, 2013.
		Three months ended						Nine months ended
		March 31,						March 31,
		2015			2014			2015			2014
	Revenue	$	357.4		$	333.3		$	1,057.90		$	986.8
	Net loss	$	(61.0	)	$	(56.7	)	$	(187.0	)	$	(145.0	)
	The Company is unable to determine the amount of revenue and net income associated with each acquisition recognized in the post-acquisition period as a result of integration activities.

Goodwill_Tables

Goodwill (Tables)	9 Months Ended
	Mar. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Schedule Of Goodwill	The following roll forward reflects the allocation of goodwill acquired in the Company’s Fiscal 2014 and 2015 acquisitions to the Company’s reporting units:
	Product Group	As of		Fiscal 2015 acquisitions		Adjustments to Fiscal 2014 acquisitions			Foreign currency translation			As of
		30-Jun-14										31-Mar-15
	Dark Fiber	$	269.9	$	0.8	$	15.3		$	(10.2	)	$	275.8
	Waves		270		—		(0.1	)		(7.6	)		262.3
	Sonet		50.3		—		—			—			50.3
	Ethernet		96.7		4.5		—			(0.2	)		101
	IP		80.4		1.9		—			(0.3	)		82
	MIG		43.7		22.3		—			—			66
	zColo		19.6		252.4		(1.1	)		(0.1	)		270.8
	Cloud		—		52.5		—			—			52.5
	Other		14.7		23.7		—			(4.9	)		33.5
	Total	$	845.3	$	358.1	$	14.1		$	(23.3	)	$	1,194.20

Intangible_Assets_Tables

Intangible Assets (Tables)	9 Months Ended
	Mar. 31, 2015
Intangible Assets Net Excluding Goodwill [Abstract]
Schedule of Intangible Assets	Identifiable acquisition-related intangible assets as of March 31, 2015 and June 30, 2014 were as follows:
		Gross		Accumulated			Net
		Carrying		Amortization
		Amount
	31-Mar-15
	Finite-Lived Intangible Assets
	Customer relationships	$	1,085.00	$	(138.2	)	$	946.8
	Trade names		0.3		(0.1	)		0.2
	Underlying rights		2.2		(0.3	)		1.9
	Total		1,087.50		(138.6	)		948.9
	Indefinite-Lived Intangible Assets
	Certifications		3.5		—			3.5
	Underlying Rights		16.9		—			16.9
	Total	$	1,107.90	$	(138.6	)	$	969.3
	30-Jun-14
	Finite-Lived Intangible Assets
	Customer relationships	$	789.2	$	(104.2	)	$	685
	Trade names		0.1		—			0.1
	Underlying rights		1.8		(0.1	)		1.7
	Total		791.1		(104.3	)		686.8
	Indefinite-Lived Intangible Assets
	Certifications		3.5		—			3.5
	Underlying rights		19.4		—			19.4
	Total	$	814	$	(104.3	)	$	709.7

LongTerm_Debt_Tables

Long-Term Debt (Tables)	9 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule of Debt	As of March 31, 2015 and June 30, 2014, long-term debt was as follows:
		March 31,			June 30,
		2015			2014
	Term Loan Facility due 2019	$	1,995.50		$	2,010.80
	8.125% Senior Secured Notes due 2020		—			750
	10.125% Senior Unsecured Notes due 2020		325.6			500
	6.00% Senior Unsecured Notes due 2023		1,430.00		—
	Total debt obligations		3,751.10			3,260.80
	Unamortized discount on Term Loan Facility due		(17.8	)		(20.6	)
	2019
	Unamortized premium on 6.00% Senior Unsecured		7.3			—
	Notes due 2023
	Carrying value of debt		3,740.60			3,240.20
	Less current portion		(20.5	)		(20.5	)
	Long-term debt, less current portion	$	3,720.10		$	3,219.70
Schedule of Fixed-Charge Coverage Ratios	Pursuant to the Credit Agreement, the Company shall not permit its Fixed Charge Coverage Ratio, which is defined in the Credit Agreement as the ratio of the Company's annualized modified EBITDA (as defined in the Credit Agreement) during the most recent quarter minus Capital Expenditures (as defined in the Credit Agreement) for the twelve month period ended as of the end of each applicable fiscal quarter to interest expense for that same period, to be less than the minimum ratio for the applicable period set forth below:
	Fiscal Quarters Ending	Minimum
		Ratio
	September 30, 2014, December 31, 2014 and March 31, 2015	2.00 to 1.0
	June 30, 2015, September 30, 2015 and December 31, 2015	2.25 to 1.0
	March 31, 2016, June 30, 2016 and September 30, 2016	2.50 to 1.0
	December 31, 2016 and for each fiscal quarter thereafter	2.75 to 1.0

Income_Taxes_Tables

Income Taxes (Tables)	9 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Provision for Income Taxes	The Company, a limited liability company, is taxed at the Holdings level.  All income tax balances resulting from the operations of Zayo Group, on a separate return basis, are reflected in these financial statements.
	The Company’s provision/(benefit) for income taxes is summarized as follows:
		Three months ended March 31,						Nine months ended March 31,
		2015			2014			2015			2014
	Current income taxes
	Federal	$	(1.7	)	$	—		$	1.4		$	—
	State		2.7			—			4.5			2.1
	Foreign		—			—			0.8			—
	Total		1		—				6.7			2.1
	Deferred income taxes
	Federal		(15.7	)		16.3			(14.7	)		29.3
	State		(5.2	)		(5.5	)		(6.4	)		(5.8	)
	Foreign		1.5			1.3			1.1			4.2
	Total		(19.4	)		12.1			(20.0	)		27.7
	Total (benefit)/provision for income taxes	$	(18.4	)	$	12.1		$	(13.3	)	$	29.8
Schedule of Income before Income Tax	The United States and foreign components of net loss before income taxes for the three and nine months ended March 31, 2015 and 2014 are as follows:
		Three months ended March 31,						Nine months ended March 31,
		2015			2014			2015			2014
	United States	$	(76.9	)	$	(20.6	)	$	(169.1	)	$	(73.7	)
	Foreign		4.8			(10.9	)		(4.5	)		(3.6	)
	Total	$	(72.1	)	$	(31.5	)	$	(173.6	)	$	(77.3	)
Schedule Of Reconciliation Of Income Tax Provision	Reconciliations 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 nine-month periods ended March 31, 2015 and 2014 are as follows:
		Three months ended March 31,						Nine months ended March 31,
		2015			2014			2015			2014
	Expected benefit at statutory rate	$	(25.3	)	$	(10.3	)	$	(60.9	)	$	(26.8	)
	Increase due to:
	Non-deductible stock-based compensation		8.8			23.4			51			62.9
	State income taxes (benefit)/provision, net of		(3.8	)		(0.9	)		(8.3	)		(3.7	)
	federal benefit
	Transaction costs not deductible for tax purposes		0.3			0.1			0.6			0.2
	Foreign tax rate differential		(0.1	)		1			0.7			(0.1	)
	Release of accrual for uncertain tax position		—			—			—			(2.6	)
	Other, net		1.7			(1.2	)		3.6			(0.1	)
	(Benefit)/provision for income taxes	$	(18.4	)	$	12.1		$	(13.3	)	$	29.8

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	9 Months Ended
	Mar. 31, 2015
Share Based Compensation [Abstract]
Schedule of Employee Service Share-based Compensation Allocation of Recognized Period Costs	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				Nine months ended
		March 31,				March 31,
	Included in:	2015		2014		2015		2014
	Operating costs	$	4.1	$	4.9	$	19.4	$	12.9
	Selling, general and administrative expenses		36.6		60.3		138.4		152.2
	Total stock-based compensation expense	$	40.7	$	65.2	$	157.8	$	165.1
	CII Common units	$	23.6	$	65.1	$	133.2	$	164.7
	CII Preferred units		0.1		0.1		0.3		0.4
	Part A restricted stock units		3.5		—		6.1		—
	Part B restricted stock units		13.5		—		18.2		—
	Total stock-based compensation expense	$	40.7	$	65.2	$	157.8	$	165.1
Summary of Part B RSU Issuance	The table below reflects the total Part B RSUs granted during each period presented, the maximum eligible shares of ZGH’s stock that the respective Part B RSU grant could be converted to ZGH’s common stock and the grant date fair value per Part B RSU:
		During the three months ended
		March 31,		December 31,
		2015		2014
	Part B RSUs granted		359,658		575,660
	Maximum eligible shares of the Company's stock		1,381,086		2,210,534
	Grant date fair value per Part B RSU	$	24.36	$	63.12

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Schedule of Financial Instruments Measured at Fair Value on a Recurring Basis	Financial instruments measured at fair value on a recurring basis are summarized below:
		Level	March 31,		June 30,
			2015		2014
	Liabilities Recorded at Fair Value in the Financial
	Statements:
	Interest rate swap	Level 2	$	3.8	$	2
	Prior to the deemed modification of the Companys stock-based compensation arrangements (See Note 9 – Stock-based Compensation), the Company recorded its stock based compensation liability at fair value.  The fair value of the Company’s stock-based compensation liability as of June 30, 2014 was $392.4.

Related_Party_Transactions_Tab

Related Party Transactions (Tables) (O V S)	9 Months Ended
	Mar. 31, 2015
O V S
Related Party Transaction [Line Items]
Revenue and Expense Transactions Recognized	The following table represents the revenue and expense transactions we recorded with OVS for the periods presented:
		Three months ended					Nine months ended
		March 31,					March 31,
		2015			2014		2015			2014
	Revenues	$	1.8		$	1.8	$	5.2		$	5.2
	Operating costs	$	(0.1	)	$	-0.3	$	(0.8	)	$	-1.1

Segment_Reporting_Tables

Segment Reporting (Tables)	9 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Summary Of Significant Financial Information	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 March 31, 2015
		Physical			Cloud and Connectivity			Other		Corp/		Total
		Infrastructure								elimination
	Revenue from external customers	$	164.3		$	163		$	13.4	$	—	$	340.7
	Segment Adjusted EBITDA	$	109.1		$	86.2		$	3.7	$	—	$	199
	Total assets	$	3,598.20		$	1,959.40		$	121.1	$	281.4	$	5,960.10
	Capital expenditures	$	82.2		$	46.7		$	1.2	$	—	$	130.1
		As of and for the nine months ended March 31, 2015
		Physical			Cloud and Connectivity			Other		Corp/		Total
		Infrastructure								elimination
	Revenue from external customers	$	466.7		$	476.5		$	42	$	—	$	985.2
	Segment Adjusted EBITDA	$	308.5		$	252.6		$	10.6	$	—	$	571.7
	Capital expenditures	$	226.8		$	145.3		$	2.8	$	—	$	374.9
		As of and for the three months ended March 31, 2014
		Physical			Cloud and Connectivity			Other		Corp/		Total
		Infrastructure								elimination
	Revenue from external customers	$	125		$	151.7		$	6.5	$	—	$	283.2
	Segment Adjusted EBITDA	$	82.4		$	82.6		$	1.9	$	—	$	166.9
	Capital expenditures	$	57.1		$	33.8		$	—	$	—	$	90.9
		As of and for the nine months ended March 31, 2014
		Physical			Cloud and Connectivity			Other		Corp/		Total
		Infrastructure								elimination
	Revenue from external customers	$	359.5		$	452.4		$	19.7	$	—	$	831.6
	Segment Adjusted EBITDA	$	237.1		$	244.7		$	5.6	$	—	$	487.4
	Capital expenditures	$	149		$	116.9		$	—	$	—	$	265.9
Reconciliation from net earnings/(loss) to Adjusted EBITDA	Reconciliation from Segment Adjusted EBITDA to net earnings/(loss) from continuing operations
		Three months ended March 31,
		2015			2014
	Segment Adjusted EBITDA	$	199		$	166.9
	Interest expense		(60.7	)		(49.1	)
	Benefit/(provision) for income taxes		18.4			(12.1	)
	Depreciation and amortization expense		(100.1	)		(84.2	)
	Transaction costs		(1.5	)		—
	Stock-based compensation		(40.7	)		(65.2	)
	Loss on extinguishment of debt		(54.9	)		—
	Foreign currency (loss)/ gain on intercompany loans		(13.2	)		0.1
	Net loss from continuing operations	$	(53.7	)	$	(43.6	)
		Nine months ended March 31,
		2015			2014
	Segment Adjusted EBITDA	$	571.7		$	487.4
	Interest expense		(161.0	)		(150.9	)
	Benefit/(provision) for income taxes		13.3			(29.8	)
	Depreciation and amortization expense		(293.0	)		(246.9	)
	Transaction costs		(6.0	)		(0.8	)
	Stock-based compensation		(157.8	)		(165.1	)
	Loss on extinguishment of debt		(85.8	)		(1.9	)
	Foreign currency (loss)/ gain on intercompany loans		(41.2	)		0.9
	Non-cash loss on investments		(0.5	)		—
	Net loss from continuing operations	$	(160.3	)	$	(107.1	)

Condensed_Consolidating_Financ1

Condensed Consolidating Financial Information (Tables)	9 Months Ended
	Mar. 31, 2015
Condensed Consolidating Financial Information [Abstract]
Schedule Of Condensed Consolidating Balance Sheet	Condensed Consolidating Balance Sheets (Unaudited)
	31-Mar-15
		Zayo Group, LLC			Guarantor Subsidiaries			Non-Guarantor Subsidiaries			Eliminations			Total
		(Issuer)
	Assets
	Current assets
	Cash and cash equivalents	$	127		$	5.7		$	25.2		$	—		$	157.9
	Trade receivables, net of allowance		50			15.4			29.1		—				94.5
	Due from related parties		10.3		—				1.4			(1.4	)		10.3
	Prepaid expenses		24.6			4.8			6.8		—				36.2
	Deferred income taxes, net		159.7		—				1.3		—				161
	Other assets		4.2			0.3			0.4		—				4.9
	Total current assets		375.8			26.2			64.2			(1.4	)		464.8
	Property and equipment, net		2,557.80			322.5			318.9		—				3,199.20
	Intangible assets, net		633.5			236			99.8		—				969.3
	Goodwill		749.9			283.9			160.4		—				1,194.20
	Debt issuance costs, net		73.9			—		—			—				73.9
	Other assets		35.3			8.9			14.5		—				58.7
	Related party receivable		284.3		—			—				(284.3	)	—
	Investment in subsidiary		491.3		—			—				(491.3	)	—
	Total assets	$	5,201.80		$	877.5		$	657.8		$	(777.0	)	$	5,960.10
	Liabilities and member's equity
	Current liabilities
	Current portion of long-term debt	$	20.5		$	—		$	—		$	—		$	20.5
	Accounts payable		24.3			3.6			6.9		—				34.8
	Accrued liabilities		124.1			14.1			43.1		—				181.3
	Due to related parties		—			1.4		—				(1.4	)	—
	Accrued interest		24.2			—		—			—				24.2
	Capital lease obligations, current		2			1.5			0.5		—				4
	Deferred revenue, current		71.1			2.8			14.6		—				88.5
	Total current liabilities		266.2			23.4			65.1			(1.4	)		353.3
	Long-term debt, non-current		3,720.10			—		—			—				3,720.10
	Related party debt, long-term	—			—				284.3			(284.3	)		—
	Capital lease obligation, non-current		5.6			19			3.9		—				28.5
	Deferred revenue, non-current		548.4			4.8			35.7		—				588.9
	Stock-based compensation liability		1.5			0.1			0.3		—				1.9
	Deferred income taxes, net		167.3			—			46.1		—				213.4
	Other long-term liabilities		13.4			10.3			2.5		—				26.2
	Total liabilities		4,722.50			57.6			437.9			(285.7	)		4,932.30
	Member's equity
	Member's interest		1,554.70			236.9			250.9			(491.3	)		1,551.20
	Accumulated other comprehensive (loss)/income		0.9		—				(22.0	)	—				(21.1	)
	Accumulated deficit		(527.8	)		34.5			(9.0	)		—			(502.3	)
	Total member's equity		1,027.80			271.4			219.9			(491.3	)		1,027.80
	Total liabilities and member's equity	$	5,750.30		$	329		$	657.8		$	(777.0	)	$	5,960.10
	Condensed Consolidating Balance Sheets (Unaudited)
	30-Jun-14
		Zayo Group,			Guarantor			Non-			Eliminations			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
		(Issuer)
	Assets
	Current assets
	Cash and cash equivalents	$	260.8		$	1			35.6		$	—		$	297.4
	Trade receivables, net		37.5			6			15.5			—			59
	Due from related parties		1.1			—			0.6			(0.8	)		0.9
	Prepaid expenses		18.9			1.4			5.3			—			25.6
	Deferred income taxes		158.9			—			1.5			—			160.4
	Other assets, current		1.9			—			0.5			—			2.4
	Total current assets		479.1			8.4			59			(0.8	)		545.7
	Property and equipment, net		2,402.40			95.2			323.8			—			2,821.40
	Intangible assets, net		584.4			29.8			95.5			—			709.7
	Goodwill		682.3			17.8			145.2			—			845.3
	Debt issuance costs, net		89.4			—			—			—			89.4
Other assets		23.6			3.3			10.9			—			37.8
Related party receivable, long-term		267.8			—			—			(267.8	)		—
Investment in subsidiary		303.7			—			—			(303.7	)		—
Total assets	$	4,832.70		$	154.5		$	634.4		$	(572.3	)	$	5,049.30
Liabilities and member’s equity
Current liabilities
Current portion of long-term debt	$	20.5		$	—		$	—		$	—		$	20.5
Accounts payable		20.7			4.3			2			—			27
Accrued liabilities		126			7			26.6			—			159.6
Accrued interest		57.1			—			—			—			57.1
Capital lease obligations, current		1.5			0.9			—			—			2.4
Due to related-parties		—			—			0.8			(0.8	)		—
Deferred revenue, current		56.9			1.4			17.1			—			75.4
Total current liabilities		282.7			13.6			46.5			(0.8	)		342
Long-term debt, non-current		3,219.70			—			—			—			3,219.70
Related party debt, long-term		—			—			267.8			(267.8	)		—
Capital lease obligations, non-current		5.6			15.6			1.7			—			22.9
Stock-based compensation liability		459.5			4			33.4			—			496.9
Deferred income taxes, net		345			22.2			25.2			—			392.4
Deferred income taxes, net		106.5			—			45.3			—			151.8
Other long-term liabilities		12.4			9.8			0.1			—			22.3
Total liabilities		4,431.40			65.2			420			(268.6	)		4,648.00
Member’s equity
Member’s interest		778			49.6			205			(303.7	)		728.9
Accumulated other comprehensive loss		—			—			14.4			—			14.4
(Accumulated deficit)/retained earnings		(376.7	)		39.7			(5.0	)		—			(342.0	)
Total member’s equity		401.3			89.3			214.4			(303.7	)		401.3
Total liabilities and member’s equity	$	4,832.70		$	154.5		$	634.4		$	(572.3	)	$	5,049.30
Schedule Of Condensed Consolidating Statements Of Operations	Condensed Consolidating Statements of Operations (Unaudited)
	For the three months ended March 31, 2015
		Zayo Group,			Guarantor			Non-			Eliminations			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
		(Issuer)
	Revenue	$	264.1		$	38.3		$	38.3		$	—		$	340.7
	Operating costs and expenses
	Operating costs (excluding depreciation and		77.5			13.4			10			—			100.9
	amortization)
	Selling, general and administrative expenses		60.6			10.4			12			—			83
	Depreciation and amortization		80.8			12.4			6.9			—			100.1
	Total operating costs and expenses		218.9			36.2			28.9			—			284
	Operating income		45.2			2.1			9.4			—			56.7
	Other expenses
	Interest expense		(56.5	)		—			(4.2	)		—			(60.7	)
	Loss on extinguishment of debt		(53.8	)		(1.0	)		(0.1	)		—			(54.9	)
	Foreign currency loss on intercompany loans		(13	)		—			(0.6	)					(13.2	)
	Other expenses, net		—			—			—			—			—
	Equity in net earnings of subsidiaries		4.4			—			—			(4.4	)		—
	Total other expense, net		(118.5	)		(1.0	)		(4.9	)		(4.4	)		(128.8	)
	(Loss)/earnings before provision for income taxes		(73.3	)		1.1			4.5			(4.4	)		(72.1	)
	(Benefit)/provision for income taxes		(19.6	)		—			1.2			—			(18.4	)
	Net (loss)/earnings	$	(53.7	)	$	1.1		$	3.3		$	(4.4	)	$	(53.7	)
	Condensed Consolidating Statements of Operations (Unaudited)
	For the nine months ended March 31, 2015
		Zayo Group,			Guarantor			Non-			Eliminations			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
		(Issuer)
	Revenue	$	770.9		$	98.8		$	115.5		$	—		$	985.2
	Operating costs and expenses
	Operating costs (excluding depreciation and		236.5			36.2			33.3			—			306
	amortization)
	Selling, general and administrative expenses		206.3			25.5			39.9			—			271.7
	Depreciation and amortization		238.4			23.2			31.4			—			293
	Total operating costs and expenses		681.2			84.9			104.6			—			870.7
	Operating income		89.7			13.9			10.9			—			114.5
	Other expenses
	Interest expense		(148.3	)		—			(12.7	)		—			(161.0	)
	Loss on extinguishment of debt		(83.7	)		(1.5	)		(0.6	)		—			(85.8	)
	Foreign currency loss on intercompany loans		(39.7	)		—			(1.5	)					(41.2	)
	Other expenses, net		(0.1	)		—			—			—			(0.1	)
	Equity in net earnings of subsidiaries		6.6			—			—			(6.6	)		—
	Total other expense, net		(265.2	)		(1.5	)		(14.8	)		(6.6	)		(288.1	)
	(Loss)/earnings before provision for income taxes		(175.5	)		12.4			(3.9	)		(6.6	)		(173.6	)
	(Benefit)/provision for income taxes		(15.2	)		0.4			1.5			—			(13.3	)
	Net (loss)/earnings	$	(160.3	)	$	12		$	(5.4	)	$	(6.6	)	$	(160.3	)
	Condensed Consolidating Statements of Operations (Unaudited)
	For the three months ended March 31, 2014
		Zayo Group,			Guarantor			Non-			Eliminations			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
		(Issuer)
	Revenue	$	240.8		$	25.7		$	16.7		$	—		$	283.2
	Operating costs and expenses
	Operating costs (excluding depreciation and		70.2			11.1			3.6			—			84.9
	amortization)
	Selling, general and administrative expenses		68.1			8			20.5			—			96.6
	Depreciation and amortization		77.1			3.5			3.6			—			84.2
	Total operating costs and expenses		215.4			22.6			27.7			—			265.7
	Operating income		25.4			3.1			(11.0	)		—			17.5
	Other expenses
	Interest expense		(49.0	)		—			(0.1	)		—			(49.1	)
Loss on extinguishment of debt		—			—			—			—			—
Foreign currency loss on intercompany loans		—			—			0.1						0.1
Other expenses, net		—			—			—			—			—
Equity in net earnings of subsidiaries		(10.1	)		—			—			10.1			—
Total other expense, net		(59.1	)		—			—			10.1			(49.0	)
(Loss)/earnings before provision for income taxes		(33.7	)		3.1			(11.0	)		10.1			(31.5	)
(Benefit)/provision for income taxes		9.9			0.8			1.4			—			12.1
Net (loss)/earnings	$	(43.6	)	$	2.3		$	(12.4	)	$	10.1		$	(43.6	)
Condensed Consolidating Statements of Operations (Unaudited)
For the Nine months ended March 31, 2014
	Zayo Group,			Guarantor			Non-			Eliminations			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
	(Issuer)
Revenue	$	711.6		$	73.1		$	46.9		$	—		$	831.6
Operating costs and expenses
Operating costs (excluding depreciation and		206.7			32.8			11			—			250.5
amortization)
Selling, general and administrative expenses		209.2			21			29.8			—			260
Depreciation and amortization		227.4			9.2			10.3			—			246.9
Total operating costs and expenses		643.3			63			51.1			—			757.4
Operating income		68.3			10.1			(4.2	)		—			74.2
Other expenses
Interest expense		(150.6	)		—			(0.3	)		—			(150.9	)
Loss on extinguishment of debt		(2.0	)		—			0.1			—			(1.9	)
Foreign currency loss on intercompany loans		—			—			0.9						0.9
Other expenses, net		0.4			—			—			—			0.4
Equity in net earnings of subsidiaries		0.3			—			—			(0.3	)		—
Total other expense, net		(151.9	)		—			0.7			(0.3	)		(151.5	)
(Loss)/earnings before provision for income taxes		(83.6	)		10.1			(3.5	)		(0.3	)		(77.3	)
(Benefit)/provision for income taxes		23.5			2.2			4.1			—			29.8
Net (loss)/earnings	$	(107.1	)	$	7.9		$	(7.6	)	$	(0.3	)	$	(107.1	)
Schedule Of Condensed Consolidating Statements Of Cash Flows	Condensed Consolidating Statements of Cash Flows
	Nine months ended March 31, 2015
		Zayo Group,			Guarantor			Non-			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
	Net cash provided by operating activities	$	331			28			43.1		$	402.1
	Cash flows from investing activities:
	Purchases of property and equipment, net of stimulus grants		(318.8	)		(27.9	)		(28.2	)		(374.9	)
	Acquisitions, net of cash acquired		(182.4	)		-601			(73.9	)		(857.3	)
	Net cash used in investing activities		(501.2	)		(628.9	)		(102.1	)		(1,232.2	)
	Cash flows from financing activities:
	Proceeds from debt		1,437.30			—			—			1,437.30
	Equity contributions		-332.9			606.7			5.9			279.7
	Principal payments on long-term debt		(939.8	)		—			—			(939.8	)
	Payment of early redemption fees on debt extinguished		(62.6	)		—			—			(62.6	)
	Principal repayments on capital lease obligations		(1.1	)		(1.1	)		(0.2	)		(2.4	)
	(Payment of)/receipt from intercompany loans		(40.4	)					40.4			—
	Payment of debt issuance costs		(18.8	)		—			—			(18.8	)
	Net cash provided by financing activities		41.7			605.6			46.1			693.4
	Effect of changes in foreign exchange rates on cash		(5.3	)		—			2.5			(2.8	)
	Net (decrease)/increase in cash and cash equivalents		(133.8	)		4.7			(10.4	)		(139.5	)
	Cash and cash equivalents, beginning of period		260.8			1			35.6			297.4
	Cash and cash equivalents, end of period	$	127			5.7			25.2		$	157.9
	Condensed Consolidating Statements of Cash Flows
	Nine months ended March 31, 2014
		Zayo Group,			Guarantor			Non-			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
	Net cash provided by operating activities	$	356.1			21.8			23.7			401.6
	Cash flows from investing activities:
	Purchases of property and equipment, net of stimulus grants		(237.0	)		(18.0	)		(10.9	)		(265.9	)
	Acquisitions, net of cash acquired		(81.3	)		(19.7	)		—			(101.0	)
	Net cash used in investing activities		(318.3	)		(37.7	)		(10.9	)		(366.9	)
	Cash flows from financing activities:
	Proceeds from debt		195			—			—			195
	Principal payments on long-term debt		(57.9	)		—			—			(57.9	)
	Equity contributions		(21.4	)		21.4			—			—
	Distribution to parent		(0.4	)		—			—			(0.4	)
	Principal repayments on capital lease obligations		(1.4	)		(5.5	)		—			(6.9	)
	Payment of debt issuance costs		(1.7	)		—			—			(1.7	)
	Net cash provided by financing activities		112.2			15.9			—			128.1
	Effect of changes in foreign exchange rates on cash		—			—			0.5			0.5
	Net (decrease)/increase in cash and cash equivalents		150			(0.0	)		13.3			163.3
	Cash and cash equivalents, beginning of period		86.8			1			3.5			91.3
	Cash and cash equivalents, end of period	$	236.8		$	1		$	16.8		$	254.6

Subsequent_Events_Tables

Subsequent Events (Tables)	9 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Schedule Of Debt Instrument Redemption Price	At any time on or after May 15, 2020, the $350.0 Senior Unsecured Notes may be redeemed, in whole or in part, at the redemption prices set forth below plus accrued and unpaid interest:
	Year	Redemption Price
	2020		103.19	%
	2021		102.13	%
	2022		101.06	%
	2023 and thereafter		100	%

Business_and_Basis_of_Presenta3

Business and Basis of Presentation (Details) (USD $)	3 Months Ended					9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014
Operating costs, excluding depreciation and amortization	$100.90	$92.80	$84.90	$85.90	$79.70	$306	$250.50	$343.30
Transfer of Zayo Professional Services		3.3	1.8	1.9	2			9
Selling, general and administrative expenses	83	124.6	96.6	87	76.4	271.7	260	384.6
Transfer of Zayo Professional Services		1	1.7	1.7	1.8			6.2
Scenario, Previously Reported [Member]
Operating costs, excluding depreciation and amortization		36.2	35.4	35	34.9			141.5
Selling, general and administrative expenses		176.9	142.7	134.2	117.4			571.2
Restatement Adjustment [Member]
Operating costs, excluding depreciation and amortization		53.3	47.7	49	42.8			192.8
Selling, general and administrative expenses		($53.30)	($47.80)	($48.90)	($42.80)			($192.80)

Business_and_Basis_of_Presenta4

Business and Basis of Presentation - Additional Information (Details) (USD $)	3 Months Ended	6 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Debt issuance costs, net	$73.90	$89.40

Acquisitions_Narrative_Details

Acquisitions (Narrative) (Details)

3 Months Ended

9 Months Ended

95 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

0 Months Ended

9 Months Ended

In Millions, except Share data, unless otherwise specified

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2015

Mar. 31, 2014

Mar. 31, 2015

Jul. 03, 2014

Jul. 03, 2014

Mar. 31, 2015

Jul. 01, 2014

Jul. 01, 2014

Jul. 01, 2014

Jul. 03, 2014

Mar. 31, 2015

Jul. 01, 2014

Jan. 06, 2015

Mar. 31, 2015

Jan. 01, 2015

Aug. 01, 2013

Mar. 31, 2015

Oct. 01, 2013

Oct. 02, 2013

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2014

Oct. 02, 2013

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2014

Mar. 04, 2014

Mar. 31, 2015

Mar. 31, 2015

Mar. 31, 2014

16-May-14

16-May-14

Mar. 31, 2015

Mar. 31, 2014

Feb. 25, 2015

Feb. 23, 2015

Mar. 31, 2015

Aug. 31, 2012

Mar. 31, 2015

Mar. 31, 2015

USD ($)

USD ($)

USD ($)

USD ($)

Acquisition

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Atlanta NAP [Member]

Atlanta NAP [Member]

Atlanta NAP [Member]

IdeaTek [Member]

IdeaTek [Member]

IdeaTek [Member]

Corelink [Member]

Corelink [Member]

Access acquisition [Member]

Access acquisition [Member]

Access acquisition [Member]

Access acquisition [Member]

Access acquisition [Member]

Fiber Link [Member]

Fiber Link [Member]

Fiber Link [Member]

Fiber Link [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

Geo [Member]

Geo [Member]

Geo [Member]

Geo [Member]

Latisys [Member]

Latisys [Member]

Latisys [Member]

Fibergate Holdings Inc [Member]

Fibergate Holdings Inc [Member]

Fibergate Holdings Inc [Member]

USD ($)

EUR (€)

USD ($)

USD ($)

EUR (€)

Call Option [Member]

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

GBP (£)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

Selling, General and Administrative Expenses [Member]

Buildings

sqft

USD ($)

mi

DataCentre

CellularTowers

MW

Market

Business Acquisition [Line Items]

Number of business combinations completed

34

Acquisition date

1-Jul-14

1-Jul-14

1-Jul-14

6-Jan-15

6-Jan-15

1-Aug-13

1-Aug-13

1-Oct-13

1-Oct-13

2-Oct-13

2-Oct-13

4-Mar-14

4-Mar-14

16-May-14

16-May-14

16-May-14

23-Feb-15

23-Feb-15

31-Aug-12

Business acquisition, percentage of voting interests acquired

96.00%

96.00%

4.00%

100.00%

100.00%

100.00%

100.00%

100.00%

100.00%

100.00%

Net consideration paid

$857.30

$101

$73.90

€ 54.10

$73.90

$52.50

$53.60

$53.60

$1.90

$40.10

$43.10

$43.10

$17.20

($0.30)

$17.50

$292.30

$677.50

Escrow deposit

11.9

8.7

Purchase price, held in escrow

5.3

3.2

4

1.8

31.4

17.6

Business acquisition, equity interest issued or issuable, number of shares

301,949

Business acquisition, equity interest issued or issuable, value assigned

1.6

Cash paid for acquisitions

0.3

292.3

174.3

118.3

Notes payable

113.4

Notes payable, related parties

69.1

Intangibles

26

21

21

24

24

0.2

18

18

19.3

19.3

11

11

61.2

41.4

243.2

243.2

Estimated useful life of acquired intangible assets

19 years

15 years

19 years

20 years

18 years

12 years

12 years

15 years

Deferred Tax Assets, Net

-38.9

38.9

-76.5

-76.5

Property plant and equipment purchase accounting adjustments

3.1

9.9

0.2

Finite lived intangible assets, purchase accounting adjustments

2

2.1

0.9

Deferred tax assets purchase accounting adjustments

2

0.7

Other current assets purchase accounting adjustments

1.9

0.4

Current liabilities purchase accounting adjustments

8.7

0.1

Refund of purchase price

2.5

Property and equipment accounting adjustments

1.7

Other assets purchase accounting adjustments

0.1

Deferred revenue purchase accounting adjustments

3.6

Deferred tax liabilities purchase accounting adjustments

1.4

Other liabilities accounting adjustments

3.7

Acquisition related costs

$1.50

$0

$6

$0.80

Additional Route Miles Acquired

1,800

Number Of Additional Cellular Towers Acquired

600

Number Of Additional Building Acquired

100

Acquired area in square feet

185,000

Critical power acquired

33

Number of data center

8

Number of market

5

Acquisitions_Schedule_of_Acqui

Acquisitions (Schedule of Acquisition) (Details) (USD $)	9 Months Ended		0 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Jul. 03, 2014	Jan. 06, 2015	Feb. 25, 2015	Feb. 23, 2015	Aug. 01, 2013	Oct. 01, 2013	Oct. 02, 2013	Mar. 04, 2014	16-May-14	Jun. 30, 2014	Jul. 01, 2014	Jan. 01, 2015
Business Acquisition [Line Items]
Acquisition date	1-Jul-14
Goodwill	$1,194.20											$845.30
Net consideration paid	857.3	101
Atlanta NAP [Member]
Business Acquisition [Line Items]
Acquisition date	1-Jul-14		1-Jul-14
Other current assets													0.2
Property and equipment													7
Deferred tax assets, net													0.1
Intangibles	21												21
Goodwill													25.6
Total assets acquired													53.9
Current liabilities													1.4
Total liabilities assumed													1.4
Net assets acquired													52.5
Net consideration paid			52.5
Neo [Member]
Business Acquisition [Line Items]
Acquisition date			1-Jul-14
Cash													4.2
Other current assets													10.5
Property and equipment													28.1
Intangibles													26.6
Goodwill													23.7
Other assets													8.9
Total assets acquired													102
Current liabilities													11.3
Deferred revenue													3.7
Deferred tax liability, net													5.7
Other liabilities													3.2
Total liabilities assumed													23.9
Net assets acquired													78.1
Less cash acquired													-4.2
Net consideration paid			73.9
IdeaTek [Member]
Business Acquisition [Line Items]
Acquisition date	6-Jan-15			6-Jan-15
Other current assets														0.8
Property and equipment														32.8
Intangibles	24													24
Goodwill														29.8
Other assets														0.1
Total assets acquired														87.5
Current liabilities														4.4
Deferred revenue														25.2
Deferred tax liability, net														4.3
Total liabilities assumed														33.9
Net assets acquired														53.6
Net consideration paid	53.6			53.6
Latisys [Member]
Business Acquisition [Line Items]
Acquisition date	23-Feb-15				23-Feb-15
Cash						9.4
Other current assets						18.8
Property and equipment						220.6
Intangibles	243.2					243.2
Goodwill						279
Other assets						5.8
Total assets acquired						776.8
Current liabilities						10.2
Deferred revenue						3.2
Deferred tax liability, net						76.5
Total liabilities assumed						89.9
Net assets acquired						686.9
Less cash acquired						-9.4
Net consideration paid						677.5
Corelink [Member]
Business Acquisition [Line Items]
Acquisition date	1-Aug-13						1-Aug-13
Cash							0.1
Other current assets							0.5
Property and equipment							15.9
Intangibles							0.2
Goodwill							3
Other assets							0.5
Total assets acquired							20.2
Current liabilities							0.7
Deferred revenue							0.2
Capital lease obligations							14.3
Deferred tax liability, net							3
Total liabilities assumed							18.2
Net assets acquired							2
Less cash acquired							-0.1
Net consideration paid							1.9
Access acquisition [Member]
Business Acquisition [Line Items]
Acquisition date	1-Oct-13							1-Oct-13
Cash								1.2
Other current assets								2.3
Property and equipment								11.5
Deferred tax assets, net								0
Intangibles		18						18
Goodwill								24
Total assets acquired								57
Current liabilities								1
Deferred revenue								5.1
Deferred tax liability, net								9.6
Total liabilities assumed								15.7
Net assets acquired								41.3
Less cash acquired								-1.2
Net consideration paid									40.1
Fiber Link [Member]
Business Acquisition [Line Items]
Acquisition date	2-Oct-13								2-Oct-13
Other current assets									0.8
Property and equipment									15.9
Deferred tax assets, net									7.7
Intangibles		19.3							19.3
Goodwill									19.8
Other assets									0.1
Total assets acquired									63.6
Current liabilities									1.3
Deferred revenue									19.2
Total liabilities assumed									20.5
Net assets acquired									43.1
Net consideration paid		43.1							43.1
CoreXchange [Member]
Business Acquisition [Line Items]
Acquisition date	4-Mar-14									4-Mar-14
Other current assets										0.5
Property and equipment										3.2
Deferred tax assets, net										0.2
Intangibles		11								11
Goodwill										3.4
Total assets acquired										18.3
Current liabilities										0.5
Deferred revenue										0.4
Capital lease obligations										0.2
Total liabilities assumed										1.1
Net assets acquired										17.2
Net consideration paid	-0.3	17.5								17.2
Geo [Member]
Business Acquisition [Line Items]
Acquisition date	16-May-14										16-May-14
Cash											13.7
Other current assets											9.2
Property and equipment											221.2
Intangibles		41.4									61.2
Goodwill											108.8
Other assets											9.8
Total assets acquired											423.9
Current liabilities											30.9
Deferred revenue											44.4
Deferred tax liability, net											38.9
Total liabilities assumed											117.9
Net assets acquired											306
Less cash acquired											-13.7
Net consideration paid											292.3
Other liabilities											$3.70

Acquisitions_Schedule_of_Defer

Acquisitions (Schedule of Deferred Tax Assets and Liabilities) (Details) (USD $)	Mar. 31, 2015	16-May-14	Feb. 23, 2015
In Millions, unless otherwise specified
Geo [Member]
Deferred income tax assets:
Net operating loss carry forwards		$2.50
Deferred revenue		3.8
Total deferred income tax assets		6.3
Deferred income tax liabilities:
Property and equipment		-33
Intangible assets		-12.2
Total deferred income tax liabilities		-45.2
Net deferred income tax liabilities	38.9	-38.9
Latisys [Member]
Deferred income tax assets:
Net operating loss carry forwards			53.9
Deferred revenue			1.3
Total deferred income tax assets			55.9
Other			0.7
Deferred income tax liabilities:
Property and equipment			-48.3
Intangible assets			-84.1
Total deferred income tax liabilities			-132.4
Net deferred income tax liabilities	($76.50)		($76.50)

Acquisitions_Schedule_of_ProFo

Acquisitions (Schedule of Pro-Forma Financial Information) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Business Combinations [Abstract]
Revenue	$357.40	$333.30	$1,057.90	$986.80
Net loss	($61)	($56.70)	($187)	($145)

Goodwill_Narrative_Details

Goodwill (Narrative) (Details) (USD $)	9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014
Goodwill [Line Items]
Goodwill	$1,194.20	$845.30
Foreign currency translation	-23.3
Adjustment to goodwill acquired	14.1
Access and Fiberlink,LLC [Member]
Goodwill [Line Items]
Adjustment to goodwill acquired		-15.8
Dark Fiber [Member]
Goodwill [Line Items]
Adjustment to goodwill acquired		-27.5
Waves [Member]
Goodwill [Line Items]
Adjustment to goodwill acquired		$27.50

Goodwill_Schedule_Of_Goodwill_

Goodwill (Schedule Of Goodwill) (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014
Goodwill [Line Items]
Goodwill, beginning Balance	$845.30
Fiscal 2015 acquisitions	358.1
Adjustments to Fiscal 2014 acquisitions	14.1
Foreign currency translation	-23.3
Goodwill, ending balance	1,194.20
Dark Fiber [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	269.9
Fiscal 2015 acquisitions	0.8
Adjustments to Fiscal 2014 acquisitions	15.3
Foreign currency translation	-10.2
Goodwill, ending balance	275.8
Waves [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	270
Adjustments to Fiscal 2014 acquisitions	-0.1
Foreign currency translation	-7.6
Goodwill, ending balance	262.3
Sonet [Member]
Goodwill [Line Items]
Goodwill, beginning Balance		50.3
Goodwill, ending balance	50.3	50.3
Ethernet [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	96.7
Fiscal 2015 acquisitions	4.5
Foreign currency translation	-0.2
Goodwill, ending balance	101
IP [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	80.4
Fiscal 2015 acquisitions	1.9
Foreign currency translation	-0.3
Goodwill, ending balance	82
MIG [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	43.7
Fiscal 2015 acquisitions	22.3
Goodwill, ending balance	66
zColo [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	19.6
Fiscal 2015 acquisitions	252.4
Adjustments to Fiscal 2014 acquisitions	-1.1
Foreign currency translation	-0.1
Goodwill, ending balance	270.8
Cloud [Member]
Goodwill [Line Items]
Fiscal 2015 acquisitions	52.5
Goodwill, ending balance	52.5
Other [Member]
Goodwill [Line Items]
Goodwill, beginning Balance	14.7
Fiscal 2015 acquisitions	23.7
Foreign currency translation	-4.9
Goodwill, ending balance	$33.50

Intangible_Assets_Schedule_of_

Intangible Assets (Schedule of Intangible Assets) (Details) (USD $)	Mar. 31, 2015	Jun. 30, 2014
In Millions, unless otherwise specified
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$1,087.50	$791.10
Accumulated Amortization	-138.6	-104.3
Total Net	948.9	686.8
Intangible Assets, Gross (Excluding Goodwill)	1,107.90	814
Intangible Assets, Net	969.3	709.7
Customer relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,085	789.2
Accumulated Amortization	-138.2	-104.2
Total Net	946.8	685
Trade names [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	0.3	0.1
Accumulated Amortization	-0.1
Total Net	0.2	0.1
Underlying rights [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	2.2	1.8
Accumulated Amortization	-0.3	-0.1
Total Net	1.9	1.7
Certifications [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, Indefinite-lived Intangibles	3.5	3.5
Easement indefinite [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, Indefinite-lived Intangibles	$16.90	$19.40

LongTerm_Debt_Summary_of_LongT

Long-Term Debt (Summary of Long-Term Debt) (Details) (USD $)	Mar. 31, 2015	Mar. 09, 2015	Jun. 30, 2014	16-May-14	Nov. 26, 2013
In Millions, unless otherwise specified
Debt Instrument [Line Items]
Debt obligations	$3,751.10	$675	$3,260.80		$1,749.80
Unamortized discount on Term Loan Facility due 2019	-17.8		-20.6
Unamortized premium on 6.00% Senior Unsecured Notes due 2023	7.3
Carrying value of debt	3,740.60		3,240.20	2,015.90
Less current portion	-20.5		-20.5
Long-term debt, less current portion	3,720.10		3,219.70
10.125% Senior Unsecured Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt obligations	325.6
Term Loan Facility due 2019 [Member] | Credit Facility [Member]
Debt Instrument [Line Items]
Debt obligations	1,995.50		2,010.80
Secured Debt [Member] | 8.125% Senior Secured First Priority Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt obligations			750
Unsecured Debt [Member] | 10.125% Senior Unsecured Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt obligations	325.6		500
Unsecured Debt [Member] | 6.00% Senior Unsecured Notes due 2023
Debt Instrument [Line Items]
Debt obligations	$1,430

LongTerm_Debt_Narrative_Detail

Long-Term Debt (Narrative) (Details) (USD $)	0 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended	0 Months Ended	3 Months Ended	0 Months Ended
In Millions, unless otherwise specified	Jan. 23, 2015	16-May-14	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014	Nov. 26, 2013	Dec. 31, 2014	Mar. 09, 2015	Aug. 13, 2012	Dec. 15, 2014	Jul. 02, 2012	Feb. 23, 2015
Debt Instrument [Line Items]
Discount on debt			$17.80		$17.80		$20.60
Debt instrument, maturity date	1-Apr-23
Proceeds from debt					1,437.30	150
Debt obligations			3,751.10		3,751.10		3,260.80	1,749.80		675
Debt issuance cost		3.2			102.1
Loss on extinguishment of debt			54.9		85.8	1.9
Debt instrument carrying amount		2,015.90	3,740.60		3,740.60		3,240.20
Increase in term loan facility, price percentage		99.50%
Redemption premium					23.8
Unamortized premium on 6.00% Senior Unsecured Notes due 2023			7.3		7.3
Unamortized debt issuance cost			73.9		73.9		89.4
Accretion of premium on debt						28.2	25.4
Unamortized debt issuance related interest			3.6	3.5	11.1	10.3
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Notional amount of derivative											750
Derivative, maturity date					30-Jun-17
Derivative, fixed interest rate											1.67%
Derivative, floor rate											1.25%
Change in fair value of interest rate swap			2.3	0	1.8	1.9
Interest Rate Derivative Assets, at Fair Value			3.8		3.8		2
Payment on interest rate derivatives			0.8	0.8	2.4	1.6
Fifth Amendment [Member]
Debt Instrument [Line Items]
Proceeds from debt								150
Sixth Amendment [Member]
Debt Instrument [Line Items]
Proceeds from debt		275
Senior Secured And Senior Unsecured Notes
Debt Instrument [Line Items]
Loss on extinguishment of debt			16.1		23.2
Senior Secured Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount													750
Debt instrument, interest rate												8.13%	8.13%
Debt Instrument Maturity Year					2020
Redemption of notes												75
Redemption price as percentage												108.00%
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount													500
Debt instrument, interest rate												10.13%	10.13%
Debt Instrument Maturity Year					2020
Redemption of notes												174.4
Redemption price as percentage												110.00%
Revolver [Member]
Debt Instrument [Line Items]
Debt instrument, face amount													250
Revolver [Member] | LIBOR [Member] | Maximum [Member]
Debt Instrument [Line Items]
Revolver interest rate								3.00%
Revolver [Member] | LIBOR [Member] | Minimum [Member]
Debt Instrument [Line Items]
Percentage over variable rate								1.00%
Revolver [Member] | Fifth Amendment [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Percentage over variable rate								2.75%
Term Loan Facility [Member]
Debt Instrument [Line Items]
Discount on debt													30
Payment towards principal					5.1
Percentage of excess cash flows committed to debt payments					50.00%
Debt instrument, maturity date					31-Jul-19
Percentage over variable rate			4.00%		4.00%		4.00%
Term Loan Facility [Member] | Fourth Amendment [Member]
Debt Instrument [Line Items]
Interest rate decrease								-0.25%
Term Loan Facility [Member] | Fourth Amendment [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate decrease								-0.50%
Original Revolver [Member]
Debt Instrument [Line Items]
Debt instrument, maturity date					31-Jul-17
Percentage over variable rate			3.00%		3.00%		3.00%
Outstanding letters of credit			0		0
Available borrowing capacity			240.8		240.8
Unused commitment, percentage					0.50%
New Term Loan Facility [Member] | Fifth Amendment [Member]
Debt Instrument [Line Items]
Debt issuance cost									1.5
Loss on extinguishment of debt									1.9
New Term Loan Facility [Member] | Fifth Amendment [Member] | Third Party Costs Cash Expense [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt									1
New Term Loan Facility [Member] | Fifth Amendment [Member] | Unamortized Debt Issuance Costs And Discount On Debt [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt									0.9
6.00% Senior Unsecured Notes due 2023
Debt Instrument [Line Items]
Debt instrument, face amount										730				700
Debt instrument, interest rate														6.00%
Proceeds from debt										1,437.30
Offering premium on debt amount										1.00%
Unamortized premium on 6.00% Senior Unsecured Notes due 2023										7.3
6.00% Senior Unsecured Notes due 2023 | Debt redemption in whole before April 1, 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage			100.00%
6.00% Senior Unsecured Notes due 2023 | Debt redemption in part before April 1, 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage			106.00%
Debt instrument, percentage of principal amount redeemed			40.00%
8.125% Senior Secured First Priority Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate										8.13%
Redemption price as percentage										105.75%
Senior Secured Notes Due Two Thousand And Twenty
Debt Instrument [Line Items]
Redemption premium			38.8		38.8
Standby Letter Of Credit [Member]
Debt Instrument [Line Items]
Outstanding letters of credit			$9.20		$9.20
Unused commitment, percentage					0.25%

LongTerm_Debt_Schedule_of_Fixe

Long-Term Debt (Schedule of Fixed-Charge Coverage Ratio) (Details)	Mar. 31, 2015
Fiscal Quarter Ending September 30, 2014 [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.00%
Fiscal Quarter Ending December 31, 2014 [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.00%
Fiscal Quarter Ending March 31, 2015 [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.00%
Fiscal Quarter Ending June 30, 2015 [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.25%
Fiscal Quarter Ending September 30, 2015 [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.25%
Fiscal Quarter Ending December 31, 2015 [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.25%
Fiscal Quarter Ending March 31, 2016 [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.50%
Fiscal Quarter Ending June 30, 2016 [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.50%
Fiscal Quarter Ending September 30, 2016 [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.50%
Fiscal Quarter Ending December 31, 2016 and thereafter [Member]
Schedule Of Debt Covenants [Line Items]
Fixed-Charge Coverage Ratio	2.75%

Income_Taxes_Schedule_Of_Provi

Income Taxes (Schedule Of Provision For Income Tax) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Current income taxes
Federal income taxes b current	($1.70)		$1.40
State income taxes b current	2.7		4.5	2.1
Foreign income taxes- current			0.8
Current Income Tax Expense (Benefit), Total	1		6.7	2.1
Deferred income taxes
Federal income taxes b deferred	-15.7	16.3	-14.7	29.3
State income taxes b deferred	-5.2	-5.5	-6.4	-5.8
Foreign income taxes deferred	1.5	1.3	1.1	4.2
Deferred Income Tax Expense (Benefit), Total	-19.4	12.1	-20	27.7
Total (benefit)/provision for income taxes	($18.40)	$12.10	($13.30)	$29.80

Income_Taxes_IncomeLoss_from_C

Income Taxes (Income/(Loss) from Continuing Operations Before Income Tax) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
United States	($76.90)	($20.60)	($169.10)	($73.70)
Foreign	4.8	-10.9	-4.5	-3.6
Loss from operations before income taxes	($72.10)	($31.50)	($173.60)	($77.30)

Income_Taxes_Schedule_Of_Recon

Income Taxes (Schedule Of Reconciliation Of Income Tax Provision) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Expected benefit at statutory rate	($25.30)	($10.30)	($60.90)	($26.80)
Non-deductible stock-based compensation	8.8	23.4	51	62.9
State income taxes (benefit)/provision, net of federal benefit	-3.8	-0.9	-8.3	-3.7
Transaction costs not deductible for tax purposes	0.3	0.1	0.6	0.2
Foreign tax rate differential	-0.1	1	0.7	-0.1
Release of accrual for uncertain tax position				-2.6
Other, net	1.7	-1.2	3.6	-0.1
Total (benefit)/provision for income taxes	($18.40)	$12.10	($13.30)	$29.80

Equity_Details

Equity (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Stockholders Equity Note [Abstract]
Capital contribution from proceeds of Holdings IPO	$279.70

StockBased_Compensation_Summar

Stock-Based Compensation (Summary of Stock-based Compensation Expense Liability and Equity Classified Awards Included on the Consolidated Statements of Operations) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$40.70	$65.20	$157.80	$165.10
Operating Costs [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	4.1	4.9	19.4	12.9
Selling, General and Administrative Expenses [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	36.6	60.3	138.4	152.2
CII [Member] | Common Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	23.6	65.1	133.2	164.7
CII [Member] | Preferred Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	0.1	0.1	0.3	0.4
Part A Restricted Stock Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	3.5		6.1
Part B Restricted Stock Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$13.50		$18.20

StockBased_Compensation_Narrat

Stock-Based Compensation (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended			3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Oct. 16, 2014	Oct. 09, 2014	Sep. 17, 2014	Sep. 30, 2014	Dec. 31, 2014	Jun. 30, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Reclassification of common unit liability to additional paid in capital			$490,200,000
Vesting date			15-May-17
Total stock-based compensation expense	40,700,000	65,200,000	157,800,000	165,100,000
Award recorded as liability	4,932,300,000		4,932,300,000							4,648,000,000
PCIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive plan termination period					10 years
CII [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized	625,000,000		625,000,000
Unrecognized compensation cost	124,100,000		124,100,000
Common stock distributed in exchange for vested preferred units						256,265
CII [Member] | Common Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost	90,600,000		90,600,000
Common stock distributed in connection with non-liquidating distribution						20,460,047
Common unit unvested						6,392,071
Common stock distributed for existing share holders						10,294,867
Total stock-based compensation expense	23,600,000	65,100,000	133,200,000	164,700,000
CII [Member] | Preferred Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	100,000	100,000	300,000	400,000
Part A Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs outstanding	494,825		494,825
Unrecognized compensation cost	15,400,000		15,400,000
Total stock-based compensation expense	3,500,000		6,100,000
Compensation expense associated with vested portion	2,900,000		5,100,000
Award recorded as liability	1,900,000		1,900,000
Part A Restricted Stock Units [Member] | Dan Caruso [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost	1,800,000		1,800,000
Total stock-based compensation expense	600,000		1,000,000
One-time grant amount							2,800,000
One-time grant shares							144,737
Annual salary							17,500	400,000
Part B Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs outstanding	935,318		935,318
Unrecognized compensation cost	28,300,000		28,300,000
Total stock-based compensation expense	$13,500,000		$18,200,000
One-time grant shares	359,658								575,660

StockBased_Compensation_Summar1

Stock-Based Compensation (Summary Of Part B RSU Issuance ) (Details) (Part B Restricted Stock Units [Member], USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Part B Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Part B RSUs granted	359,658	575,660
Maximum eligible shares of the Company's stock	1,381,086	2,210,534
Grant date fair value per Part B RSU	$24.36	$63.12

Fair_Value_Measurements_Narrat

Fair Value Measurements (Narrative) (Details) (USD $)	9 Months Ended	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2014	Mar. 09, 2015	Jun. 30, 2014	Nov. 26, 2013
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Carrying value of the notes	$3,751.10	$3,751.10			$675	$3,260.80	$1,749.80
Hypothetical annual interest expense	20
Hypothetical increase to interest rate swap fair value	9.8	9.8
Fair value of stock-based compensation liability	1.9	1.9				392.4
Interest Rate Swap [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Hypothetical interest rate increase		1.00%
Change in fair value of interest rate swap	1.8	2.3	0	1.9
Notes [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Carrying value of the notes	1,755.60	1,755.60				1,250
Fair value of the notes	1,805.90	1,805.90				1,294.80
Term Loan Facility [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Carrying value of the notes	$1,977.70	$1,977.70				$1,990.20
Floor rate	1.00%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	3.00%
Hypothetical interest rate increase	1.00%

Fair_Value_Measurements_Schedu

Fair Value Measurements (Schedule Of Financial Instruments Measured At Fair Value On A Recurring Basis) (Details) (Level 2 [Member], USD $)	Mar. 31, 2015	Jun. 30, 2014
In Millions, unless otherwise specified
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	$3.80	$2

Commitments_and_Contingencies_

Commitments and Contingencies (Narrative) (Details) (USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]
Purchase commitments	$165.50

Related_Party_Transactions_Sch

Related Party Transactions (Schedule of Transactions Recognized) (Details) (O V S, USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
O V S
Related Party Transaction [Line Items]
Revenues	$1.80	$1.80	$5.20	$5.20
Operating costs	($0.10)	($0.30)	($0.80)	($1.10)

Related_Party_Transactions_Nar

Related Party Transactions (Narrative) (Details) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2015	Jun. 30, 2014	Dec. 31, 2014
Related Party Transaction [Line Items]
Due from related parties	$10.30	$10.30	$0.90
O V S
Related Party Transaction [Line Items]
Due from related parties	0.2	0.2	0.1
Holdings [Member]
Related Party Transaction [Line Items]
Due from related parties			0.8	10.1
Dan Caruso [Member] | Aircraft Reimbursement [Member]
Related Party Transaction [Line Items]
Payable to related party settled	$0.10	$0.70

Segment_Reporting_Narrative_De

Segment Reporting (Narrative) (Details)	9 Months Ended
	Mar. 31, 2015
	segment
Segment Reporting Information [Line Items]
Contract term	1 year
Number of reportable segments	3
Physical Infrastructure [Member] | Minimum [Member]
Segment Reporting Information [Line Items]
Contract term	3 years
Physical Infrastructure [Member] | Maximum [Member]
Segment Reporting Information [Line Items]
Contract term	20 years
Lit Services [Member] | Minimum [Member]
Segment Reporting Information [Line Items]
Contract term	2 years
Lit Services [Member] | Maximum [Member]
Segment Reporting Information [Line Items]
Contract term	5 years

Segment_Reporting_Summary_of_S

Segment Reporting (Summary of Significant Financial Information) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014
Segment Reporting Information [Line Items]
Revenue from external customers	$340.70	$283.20	$985.20	$831.60
Segment Adjusted EBITDA	199	166.9	571.7	487.4
Total assets	5,960.10		5,960.10		5,049.30
Capital expenditures	130.1	90.9	374.9	265.9
Interest expense	-60.7	-49.1	-161	-150.9
Benefit/(provision) for income taxes	18.4	-12.1	13.3	-29.8
Depreciation and amortization expense	-100.1	-84.2	-293	-246.9
Transaction costs	-1.5	0	-6	-0.8
Stock-based compensation	-40.7	-65.2	-157.8	-165.1
Loss on extinguishment of debt	-54.9		-85.8	-1.9
Foreign currency (loss)/gain on intercompany loans	-13.2	0.1	-41.2	0.9
Net earnings/(loss) from continuing operations	-53.7	-43.6	-160.3	-107.1
Non-cash loss on investments			-0.5
Reportable Segments [Member] | Physical Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	164.3	125	466.7	359.5
Segment Adjusted EBITDA	109.1	82.4	308.5	237.1
Total assets	3,598.20		3,598.20
Capital expenditures	82.2	57.1	226.8	149
Reportable Segments [Member] | Zayo Cloud And Connectivity [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	163	151.7	476.5	452.4
Segment Adjusted EBITDA	86.2	82.6	252.6	244.7
Total assets	1,959.40		1,959.40
Capital expenditures	46.7	33.8	145.3	116.9
Reportable Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	13.4	6.5	42	19.7
Segment Adjusted EBITDA	3.7	1.9	10.6	5.6
Total assets	121.1		121.1
Capital expenditures	1.2		2.8
Corporate/eliminations [Member]
Segment Reporting Information [Line Items]
Total assets	$281.40		$281.40

Condensed_Consolidating_Financ2

Condensed Consolidating Financial Information (Narrative) (Details) (USD $)	Mar. 31, 2015	Mar. 09, 2015	Jun. 30, 2014	Nov. 26, 2013
In Millions, unless otherwise specified
Condensed Financial Statements Captions [Line Items]
Debt obligations	$3,751.10	$675	$3,260.80	$1,749.80
10.125% Senior Unsecured Notes due 2020 [Member]
Condensed Financial Statements Captions [Line Items]
Debt obligations	325.6
Unsecured Debt [Member] | 10.125% Senior Unsecured Notes due 2020 [Member]
Condensed Financial Statements Captions [Line Items]
Debt obligations	325.6		500
Unsecured Debt [Member] | 6.00% Senior Unsecured Notes due 2023
Condensed Financial Statements Captions [Line Items]
Debt obligations	$1,430

Condensed_Consolidating_Financ3

Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Balance Sheet) (Details) (USD $)	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013
In Millions, unless otherwise specified
Current assets
Cash and cash equivalents	$157.90	$297.40	$254.60	$91.30
Trade receivables, net of allowance	94.5	59
Due from related parties	10.3	0.9
Prepaid expenses	36.2	25.6
Deferred income taxes, net	161	160.4
Other assets	4.9	2.4
Total current assets	464.8	545.7
Property and equipment, net	3,199.20	2,821.40
Intangible assets, net	969.3	709.7
Goodwill	1,194.20	845.3
Debt issuance costs, net	73.9	89.4
Other assets	58.7	37.8
Total assets	5,960.10	5,049.30
Current liabilities
Current portion of long-term debt	20.5	20.5
Accounts payable	34.8	27
Accrued liabilities	181.3	159.6
Accrued interest	24.2	57.1
Capital lease obligations, current	4	2.4
Deferred revenue, current	88.5	75.4
Total current liabilities	353.3	342
Long-term debt, non-current	3,720.10	3,219.70
Capital lease obligation, non-current	28.5	22.9
Deferred revenue, non-current	588.9	496.9
Stock-based compensation liability	1.9	392.4
Deferred income taxes, net	213.4
Other long-term liabilities	26.2	22.3
Total liabilities	4,932.30	4,648
Member's equity
Member's interest	1,551.20	728.9
Accumulated other comprehensive (loss)/income	-21.1	14.4
Accumulated deficit	-502.3	-342
Total member's equity	1,027.80	401.3
Total liabilities and member's equity	5,960.10	5,049.30
Deferred income taxes, net	213.4	151.8
Eliminations [Member]
Current assets
Due from related parties	-1.4	-0.8
Total current assets	-1.4	-0.8
Related party receivable, long-term	-284.3	-267.8
Investment in subsidiary	-491.3	-303.7
Total assets	-777	-572.3
Current liabilities
Due to related parties	-1.4	-0.8
Total current liabilities	-1.4	-0.8
Related party debt, long-term	-284.3	-267.8
Total liabilities	-285.7	-268.6
Member's equity
Member's interest	-491.3	-303.7
Total member's equity	-491.3	-303.7
Total liabilities and member's equity	-777	-572.3
Zayo Group, LLC [Member]
Current assets
Cash and cash equivalents	127	260.8	236.8	86.8
Trade receivables, net of allowance	50	37.5
Due from related parties	10.3	1.1
Prepaid expenses	24.6	18.9
Deferred income taxes, net	159.7	158.9
Other assets	4.2	1.9
Total current assets	375.8	479.1
Property and equipment, net	2,557.80	2,402.40
Intangible assets, net	633.5	584.4
Goodwill	749.9	682.3
Debt issuance costs, net	73.9	89.4
Other assets	35.3	23.6
Related party receivable, long-term	284.3	267.8
Investment in subsidiary	491.3	303.7
Total assets	5,201.80	4,832.70
Current liabilities
Current portion of long-term debt	20.5	20.5
Accounts payable	24.3	20.7
Accrued liabilities	124.1	126
Accrued interest	24.2	57.1
Capital lease obligations, current	2	1.5
Deferred revenue, current	71.1	56.9
Total current liabilities	266.2	282.7
Long-term debt, non-current	3,720.10	3,219.70
Capital lease obligation, non-current	5.6	5.6
Deferred revenue, non-current	548.4	459.5
Stock-based compensation liability	1.5	345
Deferred income taxes, net	167.3
Other long-term liabilities	13.4	12.4
Total liabilities	4,722.50	4,431.40
Member's equity
Member's interest	1,554.70	778
Accumulated other comprehensive (loss)/income	0.9
Accumulated deficit	-527.8	-376.7
Total member's equity	1,027.80	401.3
Total liabilities and member's equity	5,750.30	4,832.70
Deferred income taxes, net		106.5
Guarantor Subsidiaries
Current assets
Cash and cash equivalents	5.7	1	1	1
Trade receivables, net of allowance	15.4	6
Prepaid expenses	4.8	1.4
Other assets	0.3
Total current assets	26.2	8.4
Property and equipment, net	322.5	95.2
Intangible assets, net	236	29.8
Goodwill	283.9	17.8
Other assets	8.9	3.3
Total assets	877.5	154.5
Current liabilities
Accounts payable	3.6	4.3
Accrued liabilities	14.1	7
Due to related parties	1.4
Capital lease obligations, current	1.5	0.9
Deferred revenue, current	2.8	1.4
Total current liabilities	23.4	13.6
Capital lease obligation, non-current	19	15.6
Deferred revenue, non-current	4.8	4
Stock-based compensation liability	0.1	22.2
Other long-term liabilities	10.3	9.8
Total liabilities	57.6	65.2
Member's equity
Member's interest	236.9	49.6
Accumulated deficit	34.5	39.7
Total member's equity	271.4	89.3
Total liabilities and member's equity	329	154.5
Non-Guarantor Subsidiaries [Member]
Current assets
Cash and cash equivalents	25.2	35.6	16.8	3.5
Trade receivables, net of allowance	29.1	15.5
Due from related parties	1.4	0.6
Prepaid expenses	6.8	5.3
Deferred income taxes, net	1.3	1.5
Other assets	0.4	0.5
Total current assets	64.2	59
Property and equipment, net	318.9	323.8
Intangible assets, net	99.8	95.5
Goodwill	160.4	145.2
Other assets	14.5	10.9
Total assets	657.8	634.4
Current liabilities
Accounts payable	6.9	2
Accrued liabilities	43.1	26.6
Due to related parties		0.8
Capital lease obligations, current	0.5
Deferred revenue, current	14.6	17.1
Total current liabilities	65.1	46.5
Related party debt, long-term	284.3	267.8
Capital lease obligation, non-current	3.9	1.7
Deferred revenue, non-current	35.7	33.4
Stock-based compensation liability	0.3	25.2
Deferred income taxes, net	46.1
Other long-term liabilities	2.5	0.1
Total liabilities	437.9	420
Member's equity
Member's interest	250.9	205
Accumulated other comprehensive (loss)/income	-22	14.4
Accumulated deficit	-9	-5
Total member's equity	219.9	214.4
Total liabilities and member's equity	657.8	634.4
Deferred income taxes, net		$45.30

Condensed_Consolidating_Financ4

Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Operations) (Details) (USD $)	3 Months Ended					9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Mar. 31, 2015	Mar. 31, 2014	Jun. 30, 2014
Revenue	$340.70		$283.20			$985.20	$831.60
Operating costs and expenses
Operating costs, excluding depreciation and amortization	100.9	92.8	84.9	85.9	79.7	306	250.5	343.3
Selling, general and administrative expenses	83	124.6	96.6	87	76.4	271.7	260	384.6
Depreciation and amortization	100.1		84.2			293	246.9
Total operating costs and expenses	284		265.7			870.7	757.4
Operating income	56.7		17.5			114.5	74.2
Other expenses
Interest expense	-60.7		-49.1			-161	-150.9
Loss on extinguishment of debt	-54.9					-85.8	-1.9
Foreign currency (loss)/gain on intercompany loans	-13.2		0.1			-41.2	0.9
Other (expense)/income, net						-0.1	0.4
Total other expenses, net	-128.8		-49			-288.1	-151.5
Loss from operations before income taxes	-72.1		-31.5			-173.6	-77.3
(Benefit)/provision for income taxes	-18.4		12.1			-13.3	29.8
Net earnings/(loss)	-53.7		-43.6			-160.3	-107.1
Zayo Group, LLC [Member]
Revenue	264.1		240.8			770.9	711.6
Operating costs and expenses
Operating costs, excluding depreciation and amortization	77.5		70.2			236.5	206.7
Selling, general and administrative expenses	60.6		68.1			206.3	209.2
Depreciation and amortization	80.8		77.1			238.4	227.4
Total operating costs and expenses	218.9		215.4			681.2	643.3
Operating income	45.2		25.4			89.7	68.3
Other expenses
Interest expense	-56.5		-49			-148.3	-150.6
Loss on extinguishment of debt	-53.8					-83.7	-2
Foreign currency (loss)/gain on intercompany loans	-13					-39.7
Other (expense)/income, net						-0.1	0.4
Equity in net earnings of subsidiaries	4.4		-10.1			6.6	0.3
Total other expenses, net	-118.5		-59.1			-265.2	-151.9
Loss from operations before income taxes	-73.3		-33.7			-175.5	-83.6
(Benefit)/provision for income taxes	-19.6		9.9			-15.2	23.5
Net earnings/(loss)	-53.7		-43.6			-160.3	-107.1
Guarantor Subsidiaries
Revenue	38.3		25.7			98.8	73.1
Operating costs and expenses
Operating costs, excluding depreciation and amortization	13.4		11.1			36.2	32.8
Selling, general and administrative expenses	10.4		8			25.5	21
Depreciation and amortization	12.4		3.5			23.2	9.2
Total operating costs and expenses	36.2		22.6			84.9	63
Operating income	2.1		3.1			13.9	10.1
Other expenses
Loss on extinguishment of debt	-1					-1.5
Total other expenses, net	-1					-1.5
Loss from operations before income taxes	1.1		3.1			12.4	10.1
(Benefit)/provision for income taxes			0.8			0.4	2.2
Net earnings/(loss)	1.1		2.3			12	7.9
Non-Guarantor Subsidiaries [Member]
Revenue	38.3		16.7			115.5	46.9
Operating costs and expenses
Operating costs, excluding depreciation and amortization	10		3.6			33.3	11
Selling, general and administrative expenses	12		20.5			39.9	29.8
Depreciation and amortization	6.9		3.6			31.4	10.3
Total operating costs and expenses	28.9		27.7			104.6	51.1
Operating income	9.4		-11			10.9	-4.2
Other expenses
Interest expense	-4.2		-0.1			-12.7	-0.3
Loss on extinguishment of debt	-0.1					-0.6	0.1
Foreign currency (loss)/gain on intercompany loans	-0.6		0.1			-1.5	0.9
Total other expenses, net	-4.9					-14.8	0.7
Loss from operations before income taxes	4.5		-11			-3.9	-3.5
(Benefit)/provision for income taxes	1.2		1.4			1.5	4.1
Net earnings/(loss)	3.3		-12.4			-5.4	-7.6
Eliminations [Member]
Other expenses
Equity in net earnings of subsidiaries	-4.4		10.1			-6.6	-0.3
Total other expenses, net	-4.4		10.1			-6.6	-0.3
Loss from operations before income taxes	-4.4		10.1			-6.6	-0.3
Net earnings/(loss)	($4.40)		$10.10			($6.60)	($0.30)

Condensed_Consolidating_Financ5

Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Cash Flows) (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net cash provided by operating activities	$402.10	$401.60
Cash flows from investing activities:
Purchases of property and equipment	-374.9	-265.9
Acquisition, net of cash acquired	-857.3	-101
Net cash used in investing activities	-1,232.20	-366.9
Cash flows from financing activities
Proceeds from debt	1,437.30	150
Equity contributions	279.7
Distribution to parent		-0.4
Principal payments on long-term debt	-939.8	-12.9
Payment of early redemption fees on debt extinguished	-62.6
Principal repayments on capital lease obligations	-2.4	-6.9
Payment of debt issuance costs	-18.8	-1.7
Net cash provided by financing activities	693.4	128.1
Proceeds from debt		195
Principal payments on long-term debt		-57.9
Effect of changes in foreign exchange rates on cash	-2.8	0.5
Net (decrease)/increase in cash and cash equivalents	-139.5	163.3
Cash and cash equivalents, beginning of year	297.4	91.3
Cash and cash equivalents, end of period	157.9	254.6
Zayo Group, LLC [Member]
Net cash provided by operating activities	331	356.1
Cash flows from investing activities:
Purchases of property and equipment	-318.8	-237
Acquisition, net of cash acquired	-182.4	-81.3
Net cash used in investing activities	-501.2	-318.3
Cash flows from financing activities
Proceeds from debt	1,437.30
Equity contributions	-332.9	-21.4
Distribution to parent		-0.4
Principal payments on long-term debt	-939.8
Payment of early redemption fees on debt extinguished	-62.6
Principal repayments on capital lease obligations	-1.1	-1.4
(Payment of)/receipt from intercompany loans	-40.4
Payment of debt issuance costs	-18.8	-1.7
Net cash provided by financing activities	41.7	112.2
Proceeds from debt		195
Principal payments on long-term debt		-57.9
Effect of changes in foreign exchange rates on cash	-5.3
Net (decrease)/increase in cash and cash equivalents	-133.8	150
Cash and cash equivalents, beginning of year	260.8	86.8
Cash and cash equivalents, end of period	127	236.8
Guarantor Subsidiaries
Net cash provided by operating activities	28	21.8
Cash flows from investing activities:
Purchases of property and equipment	-27.9	-18
Acquisition, net of cash acquired	-601	-19.7
Net cash used in investing activities	-628.9	-37.7
Cash flows from financing activities
Equity contributions	606.7	21.4
Principal repayments on capital lease obligations	-1.1	-5.5
Net cash provided by financing activities	605.6	15.9
Net (decrease)/increase in cash and cash equivalents	4.7	0
Cash and cash equivalents, beginning of year	1	1
Cash and cash equivalents, end of period	5.7	1
Non-Guarantor Subsidiaries [Member]
Net cash provided by operating activities	43.1	23.7
Cash flows from investing activities:
Purchases of property and equipment	-28.2	-10.9
Acquisition, net of cash acquired	-73.9
Net cash used in investing activities	-102.1	-10.9
Cash flows from financing activities
Equity contributions	5.9
Principal repayments on capital lease obligations	-0.2
(Payment of)/receipt from intercompany loans	40.4
Net cash provided by financing activities	46.1
Effect of changes in foreign exchange rates on cash	2.5	0.5
Net (decrease)/increase in cash and cash equivalents	-10.4	13.3
Cash and cash equivalents, beginning of year	35.6	3.5
Cash and cash equivalents, end of period	$25.20	$16.80

Subsequent_Events_Summary_of_S

Subsequent Events (Summary of Senior Unsecured Notes Redemption Price) (Details) (Subsequent Event, Unsecured Debt [Member])	0 Months Ended
	6-May-15
Debt redemption in part before April 1, 2018 [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	103.19%
2021 [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	102.13%
2022 [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	101.06%
2023 and thereafter [Member]
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage	100.00%

Subsequent_Events_Narrative_De

Subsequent Events (Narrative) (Details) (USD $)	0 Months Ended
In Millions, unless otherwise specified	Jan. 23, 2015	6-May-15	13-May-15	Mar. 31, 2015	Jul. 02, 2012	Apr. 17, 2015
Subsequent Event [Line Items]
Debt instrument, maturity date	1-Apr-23
Standby Letter Of Credit [Member]
Subsequent Event [Line Items]
Letter of credit commitment				$30
Revolver [Member]
Subsequent Event [Line Items]
Debt instrument, face amount					250
Subsequent Event
Subsequent Event [Line Items]
Senior Secured Leverage Ratio						525.00%
Subsequent Event | Seventh Amendment To Credit Agreement
Subsequent Event [Line Items]
Debt instrument maximum amount denominated or issued in foreign currency						50
Subsequent Event | Seventh Amendment To Credit Agreement | Standby Letter Of Credit [Member]
Subsequent Event [Line Items]
Letter of credit commitment						50
Subsequent Event | Unsecured Debt [Member] | Senior Notes Due 2025 [Member]
Subsequent Event [Line Items]
Debt instrument, face amount		350
Debt instrument, interest rate		6.38%
Debt instrument, maturity date		15-May-25
Subsequent Event | Unsecured Debt [Member] | Amended and Restated Credit Agreement [Member]
Subsequent Event [Line Items]
Debt instrument, maturity date			15-May-21
Subsequent Event | Unsecured Debt [Member] | Debt redemption in whole before April 1, 2018 [Member]
Subsequent Event [Line Items]
Debt instrument, redemption price, percentage		100.00%
Subsequent Event | Unsecured Debt [Member] | Before May 15, 2018
Subsequent Event [Line Items]
Debt instrument, redemption price, percentage		106.38%
Debt instrument, percentage of principal amount redeemed		40.00%
Subsequent Event | Revolver [Member] | Seventh Amendment To Credit Agreement
Subsequent Event [Line Items]
Debt instrument, face amount						450