Zayo 10-Q 14 Nov 14 2015 Q1 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	3 Months Ended
	Sep. 30, 2014
Document And Entity Information [Abstract]	'
Document Type	'10-Q
Amendment Flag	'false
Document Period End Date	30-Sep-14
Document Fiscal Year Focus	'2015
Document Fiscal Period Focus	'Q1
Entity Registrant Name	'Zayo Group LLC
Entity Central Index Key	'0001502756
Current Fiscal Year End Date	'--06-30
Entity Filer Category	'Non-accelerated Filer
Entity Common Stock, Shares Outstanding	0

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Jun. 30, 2014
Current assets	'	'
Cash and cash equivalents	$167,300,000	$297,400,000
Trade receivables, net of allowance of $2.3 and $3.4 as of September 30, 2014 and June 30, 2014, respectively	64,500,000	59,000,000
Due from related parties	2,500,000	900,000
Prepaid expenses	28,800,000	25,600,000
Deferred income taxes, net	160,300,000	160,400,000
Other assets	2,900,000	2,400,000
Total current assets	426,300,000	545,700,000
Property and equipment, net	2,895,700,000	2,821,400,000
Intangible assets, net	735,500,000	709,700,000
Goodwill	874,300,000	845,300,000
Debt issuance costs, net	85,600,000	89,400,000
Other assets	41,100,000	37,800,000
Total assets	5,058,500,000	5,049,300,000
Current liabilities	'	'
Current portion of long-term debt	20,500,000	20,500,000
Accounts payable	28,500,000	27,000,000
Accrued liabilities	160,900,000	159,600,000
Accrued interest	26,000,000	57,100,000
Capital lease obligations, current	3,100,000	2,400,000
Deferred revenue, current	92,700,000	75,400,000
Total current liabilities	331,700,000	342,000,000
Long-term debt, non-current	3,215,500,000	3,219,700,000
Capital lease obligations, non-current	23,300,000	22,900,000
Deferred revenue, non-current	512,600,000	496,900,000
Stock-based compensation liability	514,200,000	392,400,000
Deferred income taxes, net	162,000,000	151,800,000
Other long-term liabilities	20,400,000	22,300,000
Total liabilities	4,779,700,000	4,648,000,000
Commitments and contingencies (Note 11)	'	'
Member's equity	'	'
Member's interest	729,000,000	728,900,000
Accumulated other comprehensive income/(loss)	2,100,000	14,400,000
Accumulated deficit	-452,300,000	-342,000,000
Total member's equity	278,800,000	401,300,000
Total liabilities and member's equity	$5,058,500,000	$5,049,300,000

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Jun. 30, 2014
In Thousands, unless otherwise specified
Statement of Financial Position [Abstract]	'	'
Trade receivables allowance	$3,898	$3,689

Condensed_Consolidated_Stateme

Condensed Consolidated Statements Of Operations (USD $)	0 Months Ended	3 Months Ended					12 Months Ended
	Nov. 26, 2013	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2014
Income Statement [Abstract]	'	'	'	'	'	'	'
Revenue	'	$320,600,000	'	'	'	$269,700,000	'
Operating costs and expenses	'	'	'	'	'	'	'
Operating costs, excluding depreciation and amortization	'	107,300,000	92,800,000	85,000,000	85,800,000	79,700,000	343,300,000
Selling, general and administrative expenses, excluding stock-based compensation	'	156,600,000	'	'	'	'	'
Stock-based compensation	'	123,100,000	'	'	'	42,900,000	'
Selling, general and administrative expenses	'	156,600,000	124,600,000	96,600,000	87,000,000	76,400,000	384,600,000
Depreciation and amortization	'	96,000,000	'	'	'	81,000,000	'
Total operating costs and expenses	'	359,900,000	'	'	'	237,100,000	'
Operating income	'	-39,300,000	'	'	'	32,600,000	'
Other expenses	'	'	'	'	'	'	'
Interest expense	'	46,900,000	'	'	'	51,500,000	'
Loss on extinguishment of debt	1,000,000	'	'	'	'	'	'
Other (expense)/income, net	'	-14,700,000	'	'	'	700,000	'
Total other expense, net	'	-61,600,000	'	'	'	-50,800,000	'
Loss from continuing operations before provision for income taxes	'	-100,900,000	'	'	'	-18,200,000	'
Provision/(benefit) for income taxes	'	9,400,000	'	'	'	9,300,000	'
Net loss	'	($110,300,000)	'	'	'	($27,500,000)	'

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements Of Comprehensive Loss (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]	'	'
Net loss	($110,300)	($27,500)
Foreign currency translation adjustments	-12,300	9,500
Comprehensive loss	($122,600)	($18,000)

Condensed_Consolidated_Stateme2

Condensed Consolidated Statement Of Member's Equity (USD $)	Total	Members Interest [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
In Thousands
Balance at Jun. 30, 2014	$401,300	$728,900	$14,400	($342,000)
Preferred stock-based compensation	100	100	0	0
Foreign currency translation adjustments	-12,300	0	-12,300	0
Net loss	-110,300	0	0	-110,300
Balance at Sep. 30, 2014	$278,800	$729,000	$2,100	($452,300)

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements Of Cash Flows (USD $)	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
			Fiberlink [Member]	Fiberlink [Member]
Cash flows from operating activities	'	'	'	'
Net loss	($110,300,000)	($27,500,000)	'	'
Adjustments to reconcile net loss to net cash provided by operating activities	'	'	'	'
Depreciation and amortization	96,000,000	81,000,000	'	'
Non-cash interest expense	2,700,000	6,500,000	'	'
Stock-based compensation	123,100,000	42,900,000	'	'
Amortization of deferred revenues	-17,300,000	-12,600,000	'	'
Additions to deferred revenue	43,200,000	24,000,000	'	'
Provision for bad debts	600,000	400,000	'	'
Foreign currency loss/(gain) on intercompany loans	14,700,000	-600,000	'	'
Deferred income taxes	6,200,000	8,500,000	'	'
Changes in operating assets and liabilities, net of acquisitions	'	'	'	'
Trade receivables	4,000,000	7,600,000	'	'
Prepaid expenses	-2,100,000	1,600,000	'	'
Other assets	-5,100,000	-1,500,000	'	'
Accounts payable and accrued liabilities	-46,800,000	-32,800,000	'	'
Payables to related parties, net	-200,000	1,700,000	'	'
Other liabilities	9,500,000	-2,100,000	'	'
Net cash provided by operating activities of continuing operations	118,200,000	97,100,000	'	'
Cash flows from investing activities	'	'	'	'
Purchases of property and equipment	-115,300,000	-86,700,000	'	'
Acquisitions, net of cash acquired	-126,500,000	-300,000	73,900,000	0
Net cash used in investing activities of continuing operations	-241,800,000	-87,000,000	'	'
Cash flows from financing activities	'	'	'	'
Equity contributions	0	600,000	'	'
Principal repayments on long-term debt	-5,100,000	-4,100,000	'	'
Principal repayments on capital lease obligations	-700,000	-400,000	'	'
Payment of early redemption fees on debt extinguished	'	-200,000	'	'
Payment of deferred debt issuance costs	0	-200,000	'	'
Net cash (used in)/provided by financing activities of continuing operations	-5,800,000	-4,100,000	'	'
Cash flows from continuing operations	-129,400,000	6,000,000	'	'
Effect of changes in foreign exchange rates on cash	-700,000	100,000	'	'
Net increase in cash and cash equivalents	-130,100,000	6,100,000	'	'
Cash and cash equivalents, beginning of period	297,400,000	'	'	'
Cash and cash equivalents, end of period	167,300,000	97,400,000	'	'
Supplemental disclosure of non-cash, investing and financing activities:	'	'	'	'
Cash paid for interest, net of capitalized interest	73,600,000	75,000,000	'	'
Cash paid for income taxes	8,700,000	500,000	'	'
Non-cash purchases of equipment through capital leasing	1,600,000	3,300,000	'	'
Increase in accruals for purchases of property and equipment	$6,000,000	($14,200,000)	'	'

Business_and_Basis_of_Presenta

Business and Basis of Presentation	3 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Business and Basis of Presentation	'
	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.
	•	Lit services, including wavelengths, Ethernet, IP, and SONET services.
	•	Other services, provided by Zayo Professional Services and Zayo France.
	Zayo Group is wholly owned by Zayo Group Holdings, Inc. (“Holdings” or "ZGH").
	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 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 month periods ended September 30, 2014 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 continuing operations and are presented in millions of dollars.
	The Company's fiscal year ends June 30 each year, and we refer to the fiscal year ended June 30, 2014 as “Fiscal 2014” and the fiscal year ending June 30, 2015 as “Fiscal 2015.”
	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 disputed line cost billings, 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 fair values used to compute the stock-based compensation liability. 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			48.9			47.8			53.3			192.8
	Transfer of Zayo Professional Services		2			1.9			1.8			3.3			9
	Operating costs, as adjusted		$	79.7		$	85.8		$	85		$	92.8		$	343.3
	Selling, general and administrative expenses, as originally stated		$	117.4		$	134.2		$	142.7		$	176.9		$	571.2
	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, as adjusted		$	76.4		$	87		$	96.6		$	124.6		$	384.6
	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 May 28, 2014, the Financial Accounting Standards Board issued Accounting Standard Update (“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.

Acquisitions

Acquisitions	3 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Acquisitions	'
	ACQUISITIONS
	As of September 30, 2014 and since its formation, the Company has consummated 32 transactions accounted for as business combinations. The consummation of the acquisitions was 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 4% equity interest on or after December 31, 2015. The purchase consideration of €57.2 (or $78.1) 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 available 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 data center 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.
	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 Communications Infrastructure Investments, LLC ("CII") with an estimated fair value of $1.6 and cash of $0.3 ($0.3 net of cash acquired). The acquisition was considered a stock purchase for tax purposes. The cash consideration 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 consideration 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 "Revolver"). 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 $17.5 , net of cash acquired. 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 Revolver. 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 September 30, 2014, 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 CoreXchange, Geo, AtlantaNAP, and Neo. All information presented with respect to certain working capital and non-working capital acquired assets and liabilities assumed as it relates to these acquisitions is preliminary and subject to revision pending the final fair value analysis. During the three months ended September 30, 2014, the Company finalized its fair value analysis and resulting purchase accounting for the Access and Fiberlink acquisitions consummated in Fiscal 2014.
	The table below reflects the Company's estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2015 acquisitions:
			AtlantaNAP				Neo
	Acquisition date		July 1, 2014				July 1, 2014
	Cash		$	—			$	4.2
	Other current assets		0.3				13.1
	Property and equipment		9.7				42.9
	Deferred tax assets, net		0.1				—
	Intangibles		30.4				13.4
	Goodwill		13.6				25
	Other assets		—				2.4
	Total assets acquired		54.1				101
	Current liabilities		1.3				10.3
	Deferred revenue		0.3				6.3
	Deferred tax liability, net		—				6.3
	Total liabilities assumed		1.6				22.9
	Net assets acquired		52.5				78.1
	Less cash acquired		—				(4.2		)
	Net consideration paid		$	52.5			$	73.9
	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		August 1, 2013				October 1, 2013			October 2, 2013		March 4, 2014		May 16, 2014
	Cash		$	0.1			$	1.2		$	—	$	—	$	13.7
	Other current assets		0.5				2.3			0.8		0.7		10.7
	Property and equipment		15.9				11.5			15.9		3		219.5
	Deferred tax assets, net		—				—			7.7		0.2		—
	Intangibles		0.2				18			19.3		10.1		61.2
	Goodwill		3				24			19.8		4.7		90.2
	Other assets		0.5				—			0.1		—		9.9
	Total assets acquired		20.2				57			63.6		18.7		405.2
	Current liabilities		0.7				1			1.3		0.6		16.9
	Deferred revenue		0.2				5.1			19.2		0.4		44.3
	Other liabilities		14.3				—			—		0.2		—
	Deferred tax liability, net		3				9.6			—		—		38
	Total liabilities assumed		18.2				15.7			20.5		1.2		99.2
	Net assets acquired		2				41.3			43.1		17.5		306
	Less cash acquired		(0.1		)		(1.2		)	—		—		(13.7		)
	Net consideration paid		$	1.9			$	40.1		$	43.1	$	17.5	$	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, $30.4; and Neo, $13.4; Fiscal 2014 acquisitions - Corelink, $0.2; Access, $18.0; FiberLink, $19.3; CoreXchange, $10.1; and Geo, $61.2. The Company has not yet finalized the valuation of acquired customer relationships for CoreXchange, Geo, AtlantaNAP and Neo. For Fiscal 2015, the Company estimated the useful life of the acquired customer relationships to be approximately 11 years for AtlantaNAP and 15 years for Neo. For Fiscal 2014, the Company estimated the useful life of the acquired customer relationships to be approximately 20 years for Access, 12 years for Corelink and Geo, 11 years for CoreXchange, and 18 years for FiberLink.
	The previous owners of Geo had entered into various agreements, including IRU agreements with other telecommunication service providers to lease fiber and other bandwidth infrastructure in exchange for upfront cash payments. The Company accounted for acquired deferred revenue at its acquisition date fair value, which was determined utilizing the market approach. The market approach incorporated the actual up-front payments received by Geo under contracts entered within 18 months of the acquisition, as those were recent market transactions between parties unrelated to the Company. A fair value of $44.3 was assigned to the acquired deferred revenue balance of Geo. The acquired deferred revenue is being recognized over a weighted average remaining contract term of 9.7 years for Geo.
	Purchase Accounting Estimates Associated with Deferred Taxes
	Based on the Company’s fair value assessment related to deferred tax assets acquired in the Geo acquisition, a value of $38.0 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 carryforwards	$	2.5
Deferred revenue	4.4
Total deferred income tax assets	6.9
Deferred income tax liabilities:
Property and equipment	(32.7		)
Intangible assets	(12.2		)
Total deferred income tax liabilities	(44.9		)
Net deferred income tax liabilities	$	(38.0	)
Adjustments to Purchase Accounting Estimates Associated with Prior Year Acquisitions
Access and FiberLink
During the quarter ended September 30, 2014, 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 the filing of the Company's Annual Report on Form 10-K on September 29, 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.
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 $3.2 and $0.6 during the three months ended September 30, 2014 and 2013, 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 and Neo as if the acquisitions occurred on July 1, 2013. The pro forma loss for the quarters ended September 30, 2014 and 2013 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 (in millions) 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 September 30,
	2014				2013
Revenue	$	320.6			$	299
Loss from operations	$	(110.3	)		$	(30.0	)
The Company is unable to determine the amount of revenue associated with each acquisition recognized in the post-acquisition period as a result of integration activities.

SpinOff_Of_Business

Spin-Off Of Business	3 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Spin-Off Of Business	'
	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	3 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill	'
	GOODWILL
	The Company’s goodwill balance was $874.3 and $845.3 as of September 30, 2014 and June 30, 2014, respectively. Additions to goodwill during the three months ended September 30, 2014 relate to the acquisitions of AtlantaNAP and Neo (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"), and Other (includes ZPS and Zayo France). The following rollforward reflects the allocation of goodwill acquired in the Company's Fiscal 2014 and 2015 acquisitions to the Company's reporting units:
		Dark Fiber			Waves			SONET		Ethernet			IP			MIG		zColo		Other		Total
	As of June 30, 2014	$	269.9		$	270		$	50.3	$	96.7		$	80.4		$	43.7	$	19.6	$	14.7	$	845.3
	Additions:
	AtlantaNAP	—			—			—		—			—			—		13.6		—		13.6
	Neo	—			—			—		—			—			—		—		23.2		23.2
	Foreign currency translation and other	(4.4		)	(3.4		)	—		(0.1		)	(0.1		)	—		0.2		—		(7.8		)
	As of September 30, 2014	$	265.5		$	266.6		$	50.3	$	96.6		$	80.3		$	43.7	$	33.4	$	37.9	$	874.3
	During the three months ended September 30, 2014, goodwill decreased by $6.7 due to foreign currency movements impacting goodwill allocated to the U.K. and France operations. In addition, the Company recorded purchase accounting adjustments to acquisitions closed during the past twelve months, which resulted in a net decrease to goodwill of $1.1 during the first quarter of Fiscal 2015. The Company did not recast the previously reported consolidated balance sheet as of June 30, 2014 and statement of operations for the year ended June 30, 2014 due to the immaterial effect of these adjustments.
	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 reporting unit of $27.5 and an offsetting decrease in goodwill allocated to the Dark Fiber reporting unit.

Intangible_Assets

Intangible Assets	3 Months Ended
	Sep. 30, 2014
Intangible Assets, Net (Excluding Goodwill) [Abstract]	'
Intangible Assets	'
	INTANGIBLE ASSETS
	Identifiable acquisition-related intangible assets as of September 30, 2014 and June 30, 2014 were as follows:
		Gross		Accumulated			Net
		Carrying		Amortization
		Amount
	30-Sep-14
	Finite-Lived Intangible Assets
	Customer relationships	$	825	$	(113.2	)	$	711.8
	Trade names	0.1		—			0.1
	Underlying rights	1.7		(0.1		)	1.6
		826.8		(113.3		)	713.5
	Indefinite-Lived Intangible Assets
	Certifications	3.5		—			3.5
	Underlying rights	18.5		—			18.5
	Total	$	848.8	$	(113.3	)	$	735.5
	June 30, 2014
	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
		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	3 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	LONG-TERM DEBT
	As of September 30, 2014 and June 30, 2014, long-term debt was as follows:
	(dollars in millions)	September 30,			June 30,
		2014			2014
	Term Loan Facility due 2019	$	2,005.70		$	2,010.80
	8.125% Senior Secured Notes due 2020	750			750
	10.125% Senior Unsecured Notes due 2020	500			500
	Total debt obligations	3,255.70			3,260.80
	Unamortized discount on Term Loan Facility due 2019	(19.7		)	(20.6		)
	Carrying value of debt	3,236.00			3,240.20
	Less current portion	(20.5		)	(20.5		)
	Long-term debt, less current portion	$	3,215.50		$	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 "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 three months ended September 30, 2014 and 2013, 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, effective November 26, 2013, 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.
	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 $1.0 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.
	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.
	The Term Loan Facility bears interest at LIBOR plus 3.0% with a minimum LIBOR rate of 1.0%. The Revolver bears interest at LIBOR plus 2.75% (based on the Company's current leverage ratio). Interest rates on the Term Loan Facility and Revolver as of September 30, 2014 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.
	As of September 30, 2014, no amounts were outstanding under the Revolver. Standby letters of credit were outstanding in the amount of $6.4 as of September 30, 2014, leaving $243.6 available under the Revolver as of September 30, 2014. 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 September 30, 2014.
	Debt issuance costs
	In connection with the Notes offering, Revolver and Term Loan Facility and the subsequent amendments thereto, the Company incurred debt issuance costs of $114.8 (net of extinguishments). These costs are being amortized to interest expense over the respective terms of the underlying debt instruments using the effective interest method, unless extinguished earlier, at which time the related unamortized costs are to be immediately expensed.
	The balance of debt issuance costs as of September 30, 2014 and June 30, 2014 was $85.6 and $89.4, net of accumulated amortization of $29.2 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 $3.8 and $3.4 during the three months ended September 30, 2014 and 2013, 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 months ended September 30, 2014 and 2013, respectively, $(2.0) and $2.3 was recorded as an (decrease)/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 $0.1 and $2.0 is included in “Other long term liabilities” in the Company’s consolidated balance sheet as of September 30, 2014 and June 30, 2014, respectively.

Income_Taxes

Income Taxes	3 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	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 from continuing operations is summarized as follows:
		Three months ended September 30,
			2014				2013
	Current income taxes
	Federal		$	1.5			$	—
	State		0.9				0.8
	Foreign		0.8				—
	Total		3.2				0.8
	Deferred income taxes
	Federal		6.3				6.9
	State		0.2				0.2
	Foreign		(0.3		)		1.4
	Total		6.2				8.5
	Total provision for income taxes		$	9.4			$	9.3
	The United States and foreign components of income/(loss) from continuing operations before income taxes for the three months ended September 30, 2014 and 2013 are as follows:
		Three months ended September 30,
		2014				2013
	United States	$	(92.3	)		$	(22.6	)
	Foreign	(8.6		)		4.4
	Total	$	(100.9	)		$	(18.2	)
	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-month periods ended September 30, 2014 and 2013 are as follows:
		For the three months ended September 30,
		(in millions)
		2014				2013
	Expected benefit at statutory rate	$	(35.3	)		$	(6.4	)
	Increase due to:
	Non-deductible stock-based compensation	47.3				17
	State income taxes benefit, net of federal benefit	(4.5		)		(1.1		)
	Transaction costs not deductible for tax purposes	0.2				0.2
	Foreign tax rate differential	1.1				(0.7		)
	Other, net	0.6				0.3
	Provision for income taxes	$	9.4			$	9.3
	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. The effective tax rate is significantly affected by the amount of non-deductible stock-based compensation recognized during the year and given the significant assumptions inherent in the determination of this item, management is not able to reliably estimate the annual amount expected to impact the effective tax rate. As such, the tax effect of non-deductible stock-based compensation is recognized in each interim period in which the stock-based compensation is recorded.

Equity

Equity	3 Months Ended
	Sep. 30, 2014
Stockholders' Equity Note [Abstract]	'
Equity	'
	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 15 - Subsequent Events. 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. Prior to October 16, 2014, the Company was controlled by the CII Board of Directors, which was in turn controlled by the members of CII in accordance with the rights specified in the CII operating agreement.

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Sep. 30, 2014
Share-based Compensation [Abstract]	'
Stock-Based Compensation	'
	STOCK-BASED COMPENSATION
	The following table summarizes the Company’s stock-based compensation expense liability and equity classified awards included on the consolidated statements of operations.
		Three Months Ended September 30,
		2014		2013
	Included in:
	Operating costs	$	14.4	$	3.7
	Selling, general and administrative expenses	108.7		39.2
		$	123.1	$	42.9
	Liability Classified Awards
	As of September 30, 2014, the Company had been 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.
	As of September 30, 2014, CII had eleven classes of common units with different liquidation preferences: Class A through Class K units. Common units are issued to employees and to independent directors of the Company and are allocated by the Chief Executive Officer and the board of managers of CII on the terms and conditions specified in the employee equity agreement. The common units do not have voting rights. At September 30, 2014, 549,268,807 common units of CII were issued and outstanding to employees, directors, and affiliates of the Company and 75,731,193 common units of CII were available to be issued. As of June 30, 2014, 552,512,338 common units of CII were issued and outstanding to employees, directors, and affiliates of the Company and 72,487,662 common units of CII were available to be issued. CII has a separate class of common units of CII issued to employees of ZPS ("ZPS Class A"). As of September 30, 2014, 18,345,417 ZPS Class A common units were issued and outstanding, and no units were available to be issued. As of June 30, 2014, 18,710,000 ZPS Class A common units were issued and outstanding, and no units were available to be issued.
	The common units are considered to be stock-based compensation with terms that require the awards to be classified as liabilities due to cash settlement features. As such, the Company accounts for the vested awards as a liability and re-measures the liability to fair value at each reporting date until the date of settlement.
	As of September 30, 2014 and June 30, 2014, the estimated fair value of the common units was as follows:
	Common Unit Class	September 30, 2014		June 30, 2014
		(estimated per unit value)
	Class A	$	2.97	$	2.47
	Class B	2.68		2.22
	Class C	2.31		1.92
	Class D	2.25		1.86
	Class E	1.95		1.62
	Class F	1.74		1.44
	Class G	0.99		0.82
	Class H	0.84		0.7
	Class I	0.54		0.45
	Class J	0.39		0.33
	Class K	0.34		0.29
	ZPS Class A	0.09		0.09
	The Company recognized stock-based compensation expense and a related increase to the stock-based compensation liability for common unit grants of $123.0 and $42.7 during the three months ended September 30, 2014 and 2013, respectively.
	The liability associated with the common units was $514.2 and $392.4 as of September 30, 2014 and June 30, 2014, respectively. As of September 30, 2014, common units with an estimated fair value of $136.5 were unvested. The fair value of the unvested common units will be recognized as stock-based compensation expense over the next three years. See also Note 15 - Subsequent Events.
	The holders of common units of CII are not entitled to transfer their units or receive dividends or distributions, except at the discretion of CII's board of managers. Upon a liquidation of CII, or upon a non-liquidating distribution, the holders of common units share in the proceeds after the capital contributions of the CII preferred unit holders plus their priority return of 6% per annum has been reimbursed. The remaining proceeds from a liquidation event are distributed between the preferred and common unit holders on a scale ranging from 85% to the preferred unit holders and 15% to the common unit holders to 80% to the preferred unit holders and 20% to the common unit holders. The percentage allocated to the common unit holders is dependent upon the return multiple realized by the preferred unit holders as defined in the CII operating agreement. The maximum incremental allocation of proceeds from a liquidation event to common unit holders, of 20%, occurs if the return multiple realized by a preferred unit holder reaches 3.5 times each respective preferred holder's combined capital contributions.
	Each class of common units has a liquidation threshold. Holders of a respective class of common units begin to receive a portion of the proceeds from a liquidity event once the aggregate distributions previously made with respect to issued common units of earlier classes are equal to or greater than the liquidation threshold of the respective common unit class. Common unit holders of each of the following classes begin sharing in the proceeds of a liquidation event once the total amount distributed to earlier classes reaches the following liquidation thresholds:
	Common Unit Class	Liquidation Threshold
	Class A	$	—
	Class B	15
	Class C	40
	Class D	45
	Class E	75
	Class F	95
	Class G	235
	Class H	290
	Class I	435
	Class J	515
	Class K	545
	Equity Classified Awards
	CII has issued preferred units 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 account of $0.1 and $0.2 for the three months ended September 30, 2014 and 2013, respectively, including compensation recorded for preferred units granted in earlier periods.

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	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 September 30, 2014 and June 30, 2014 due to the short maturity of these instruments.
	The carrying value of the Company’s note obligations reflects the original amounts borrowed and was $1,250.0 as of September 30, 2014 and June 30, 2014. Based on market interest rates for debt of similar terms and average maturities, the fair value of the Company's notes as of September 30, 2014 and June 30, 2014 was estimated to be $1,308.5 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 $1,986.0 and $1,990.2 as of September 30, 2014 and June 30, 2014, respectively. The Company’s term loan 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 Facility of one percentage point above the 1.0% LIBOR floor would increase the Company’s annual interest expense by approximately $24.6.
	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 $(2.0) and $2.3 were recorded as a (decrease)/increase to interest expense during the three months ended September 30, 2014 and 2013, respectively. A hypothetical increase in LIBOR rates of 100 basis points would increase the fair value of the interest rate swaps by approximately $16.5.
	The Company records its stock-based compensation liability at its estimated fair value. Financial instruments measured at fair value on a recurring basis are summarized below:
		Level	30-Sep-14		30-Jun-14
	Liabilities Recorded at Fair Value in the Financial Statements:
	Interest rate swap	Level 2	$	—	$	2
	Stock-based compensation liability	Level 3	$	514.2	$	392.4

Commitments_And_Contingencies

Commitments And Contingencies	3 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Commitments And Contingencies	'
	COMMITMENTS AND CONTINGENCIES
	Purchase commitments
	At September 30, 2014, the Company was contractually committed for $151.0 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	3 Months Ended
	Sep. 30, 2014
Related Party Transaction, Due from (to) Related Party [Abstract]	'
Related Party Transactions	'
	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 recognized with Onvoy for the periods presented:
		Three Months Ended September 30,
		2014			2013
	Revenues	$	1.7		1.7
	Operating costs	$	(0.3	)	(0.4	)
	As of September 30, 2014 and June 30, 2014, the Company had a balance due from OVS in the amount of nil and $0.6, respectively.
	As of September 30, 2014 and June 30, 2014, the Company had a balance due from Holdings in the amount of $4.5 and $0.7, respectively, related to costs paid by the Company in connection with Holdings' initial public offering completed on October 22, 2014. See Note 15 - Subsequent Events.
	Dan Caruso, the Company’s Chief Executive Officer, 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 months ended September 30, 2014, the Company reimbursed Mr. Caruso $0.4 for his business use of the aircraft.
	On July 2, 2012, Matthew Erickson, an officer of the Company, purchased $0.6 in aggregate principal amount of the Company’s Senior Unsecured Notes at the offering price for such notes. Mr. Erickson qualifies as an “accredited investor” (as defined in Rule 501 under the Securities Act) and purchased the notes on terms available to other investors.

Segment_Reporting

Segment Reporting	3 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Segment Reporting	'
	SEGMENT REPORTING
	An operating segment is a component of an entity that has all of the following characteristics:
	•	It engages in business activities from which it may earn revenues and incur expenses.
	•	Its operating results are regularly reviewed by the entity’s chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance.
	•	Its discrete financial information is available.
	The Company’s chief operating decision maker is its Chief Executive Officer.
	The Company uses the management approach to determine the segment financial information that should be disaggregated and presented separately in the Company’s notes to its financial statements. The management approach is based on the manner by which management has organized the segments within the Company for making operating decisions, allocating resources, and assessing performance. The Company evaluates performance and makes decisions about allocating resources to its operating segments based on financial measures such as revenue and adjusted EBITDA (as defined below).
	The Company’s individual strategic product groups ("SPGs") are organized into three reportable segments based on the similarities of business activities: Physical Infrastructure, Lit Services and Other. The Physical Infrastructure reporting segment is comprised of the following SPGs: Dark Fiber, Mobile Infrastructure, and zColo. The Lit Services reporting segment is comprised of the following SPGs: Wavelengths, Ethernet, IP and SONET. SPGs report directly to the segment managers who are responsible for the operations and financial results for the Physical Infrastructure, Lit Services and Other reportable segments. The segment managers for each of the Physical Infrastructure, Lit Services 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 tend to range from three to twenty years.
	Lit Services.  The Lit Services 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 lit services include wavelength, Ethernet, IP, and SONET services with capacity ranging from 1.54Mb to 100G. The Company targets customers who require a minimum of 10G of bandwidth across their networks. Lit Services 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 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-based bandwidth infrastructure.
	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 on an intercompany loan, and impairment of cost method investment. 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 September 30, 2014
		Physical Infrastructure			Lit Services			Other			Corp/		Total
											elimination
	Revenue from external customers	$	149.7		$	156.1		$	14.8		$	—	$	320.6
	Segment Adjusted EBITDA	$	97.3		$	82.2		$	3.5		$	—	$	183
	Total assets	$	2,869.50		$	1,772.60		$	131.8		$	284.6	$	5,058.50
	Capital expenditures	$	(68.0	)	$	(46.1	)	$	(1.2	)	$	—	$	(115.3	)
		As of and for the three months ended September 30, 2013
		Physical Infrastructure			Lit Services			Other			Corp/		Total
											elimination
	Revenue from external customers	$	113.6		$	149.4		$	6.7		$	—	$	269.7
	Segment Adjusted EBITDA	$	74.4		$	80.9		$	1.9		$	—	$	157.2
	Capital expenditures	$	(45.2	)	$	(41.5	)	$	—		$	—	$	(86.7	)
		As of June 30, 2014
		Physical Infrastructure			Lit Services			Other			Corp/		Total
											elimination
	Total assets	$	2,851.80		$	1,739.10		$	43.1		$	415.3	$	5,049.30
	Reconciliation Total Segment Adjusted EBITDA to from net earnings/(loss) from continuing operations
		Three months ended September 30,
		2014			2013
	Segment Adjusted EBITDA	$	183		$	157.2
	Interest expense	(46.9		)	(51.5		)
	Provision for income taxes	(9.4		)	(9.3		)
	Depreciation and amortization expense	(96.0		)	(81.0		)
	Transaction costs	(3.2		)	(0.6		)
	Stock-based compensation	(123.1		)	(42.9		)
	Foreign currency loss/(gain) on intercompany loans	(14.7		)	0.6
	Net loss from continuing operations	$	(110.3	)	$	(27.5	)

Condensed_Consolidating_Financ

Condensed Consolidating Financial Information	3 Months Ended
	Sep. 30, 2014
Condensed Consolidating Financial Information [Abstract]	'
Condensed Consolidating Financial Information	'
	CONDENSED CONSOLIDATING FINANCIAL INFORMATION
	As discussed in Note 6 – Long-Term Debt, on July 2, 2012, the Company co-issued, with its 100% owned finance subsidiary, Zayo Capital, $750.0 Senior Secured Notes and $500.0 Senior Unsecured Notes. The Notes are fully and unconditionally guaranteed, jointly and severally, on a senior secured 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 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)
	September 30, 2014
		Zayo Group,			Guarantor			Non-			Eliminations			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
		(Issuer)
	Assets
	Current assets
	Cash and cash equivalents	$	146.1		$	1		$	20.2		$	—		$	167.3
	Trade receivables, net	31.6			6.9			26			—			64.5
	Due from related parties	2.4			—			1.1			(1.0		)	2.5
	Prepaid expenses	19.2			3.1			6.5			—			28.8
	Deferred income taxes	158.9			—			1.4			—			160.3
	Other assets	1.5			—			1.4			—			2.9
	Total current assets	359.7			11			56.6			(1.0		)	426.3
	Property and equipment, net	2,438.20			111.6			345.9			—			2,895.70
	Intangible assets, net	574.9			58.5			102.1			—			735.5
	Goodwill	682.4			31.7			160.2			—			874.3
	Debt issuance costs, net	85.6			—			—			—			85.6
	Other assets	24.5			4.2			12.4			—			41.1
	Related party receivable, long-term	301.5			—			—			(301.5		)	—
	Investment in subsidiary	360.3			—			—			(360.3		)	—
	Total assets	$	4,827.10		$	217		$	677.2		$	(662.8	)	$	5,058.50
	Liabilities and member’s equity
	Current liabilities
	Current portion of long-term debt	$	20.5		$	—		$	—		$	—		$	20.5
	Accounts payable	20.7			2.2			5.6			—			28.5
	Accrued liabilities	128.9			7.8			24.2			—			160.9
	Accrued interest	26			—			—			—			26
	Capital lease obligations, current	1.6			1.5			—			—			3.1
	Due to related parties	—			—			1			(1.0		)	—
	Deferred revenue, current	59.8			1.5			31.4			—			92.7
	Total current liabilities	257.5			13			62.2			(1.0		)	331.7
	Long-term debt, non-current	3,215.50			—			—			—			3,215.50
	Related party debt, long-term	—			—			301.5			(301.5		)	—
	Capital lease obligations, non-current	5.6			16.1			1.6			—			23.3
	Deferred revenue, non-current	483.5			4			25.1			—			512.6
	Stock-based compensation liability	452.4			28.5			33.3			—			514.2
	Deferred income taxes, net	112.9			—			49.1			—			162
	Other long-term liabilities	10.1			10.1			0.2			—			20.4
	Total liabilities	4,537.50			71.7			473			(302.5		)	4,779.70
	Member’s equity
	Member’s interest	776.6			104			215.8			(367.4		)	729
	Accumulated other comprehensive income	—			—			2.1			—			2.1
	(Accumulated deficit)/retained earnings	(487.0		)	41.3			(13.7		)	7.1			(452.3		)
	Total member’s equity	289.6			145.3			204.2			(360.3		)	278.8
	Total liabilities and member’s equity	$	4,827.10		$	217		$	677.2		$	(662.8	)	$	5,058.50
	Condensed Consolidating Balance Sheets (Unaudited)
	June 30, 2014
		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
Deferred income taxes, net	—			—			—			—			—
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
Deferred revenue, non-current	459.5			4			33.4			—			496.9
Deferred income taxes, net	345			22.2			25.2			—			151.8
Stock-based compensation liability	106.5			—			45.3			—			392.4
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 September 30, 2014
	Zayo Group,			Guarantor			Non-			Eliminations			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
	(Issuer)
Revenue	$	257.2		$	24.8		$	38.6		$	—		$	320.6
Operating costs and expenses
Operating costs (excluding depreciation and amortization)	88			7.6			11.7			—			107.3
Selling, general and administrative expenses	126.9			10.7			19			—			156.6
Depreciation and amortization	80			4.5			11.5			—			96
Total operating costs and expenses	294.9			22.8			42.2			—			359.9
Operating income	(37.7		)	2			(3.6		)	—			(39.3		)
Other expenses
Interest expense	(42.4		)	(0.1		)	(4.4		)	—			(46.9		)
Other income, net	(14.1		)	—			(0.6		)	—			(14.7		)
Equity in net earnings of subsidiaries	(7.1		)	—			—			7.1			—
Total other (expense)/income, net	(63.6		)	(0.1		)	(5.0		)	7.1			(61.6		)
(Loss)/earnings before provision for income taxes	(101.3		)	1.9			(8.6		)	7.1			(100.9		)
Provision for income taxes	9			—			0.4			—			9.4
Net (loss)/earnings	$	(110.3	)	$	1.9		$	(9.0	)	$	7.1		$	(110.3	)
Condensed Consolidating Statements of Operations (Unaudited)
For the three months ended September 30, 2013
	Zayo Group,			Guarantor			Other Non-			Eliminations			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
	(Issuer)
Revenue	$	238.8		$	16.1		$	14.8		$	—		$	269.7
Operating costs and expenses
Operating costs (excluding depreciation and amortization)	70.6			5.7			3.4			—			79.7
Selling, general and administrative expenses	66.5			5.6			4.3			—			76.4
Depreciation and amortization	75.4			2.3			3.3			—			81
Total operating costs and expenses	212.5			13.6			11			—			237.1
Operating income	26.3			2.5			3.8			—			32.6
Other expenses
Interest expense	(49.2		)	(2.2		)	(0.1		)	—			(51.5		)
Other income, net	—			—			0.7			—			0.7
Equity in net earnings of subsidiaries	3.3			—			—			(3.3		)	—
Total other (expense)/income, net	(45.9		)	(2.2		)	0.6			(3.3		)	(50.8		)
(Loss)/earnings before provision for income taxes	(19.6		)	0.3			4.4			(3.3		)	(18.2		)
Provision for income taxes	7.8			—			1.5			—			9.3
Net (loss)/earnings	$	(27.4	)	$	0.3		$	2.9		$	(3.3	)	$	(27.5	)
Condensed Consolidating Statements of Cash Flows (Unaudited)
For the three months ended September 30, 2014
	Zayo Group,			Guarantor			Non-			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
	(Issuer)
Net cash provided by operating activities	$	102.3		$	9		$	6.9		$	118.2
Cash flows from investing activities:
Purchases of property and equipment	(98.5		)	(10.7		)	(6.1		)	(115.3		)
Acquisitions, net of cash acquired	(0.1		)	(52.5		)	(73.9		)	(126.5		)
Net cash used in investing activities	(98.6		)	(63.2		)	(80.0		)	(241.8		)
Cash flows from financing activities:
Equity contributions/(distributions)	(69.6		)	54.6			15			—
Dividend received/(paid)	—			—			—			—
Principal repayments on long-term debt	(5.1		)	—			—			(5.1		)
(Payment of)/receipt from intercompany loan	(43.4		)	—			43.4			—
Principal repayments on capital lease obligations	(0.3		)	(0.4		)	—			(0.7		)
Net cash (used in)/provided by financing activities	(118.4		)	54.2			58.4			(5.8		)
Effect of changes in foreign exchange rates on cash	—			—			(0.7		)	(0.7		)
Net decrease in cash and cash equivalents	(114.7		)	—			(15.4		)	(130.1		)
Cash and cash equivalents, beginning of period	260.8			1			35.6			297.4
Cash and cash equivalents, end of period	$	146.1		$	1		$	20.2		$	167.3
Condensed Consolidating Statements of Cash Flows (Unaudited)
For the three months ended September 30, 2013
	Zayo Group,			Guarantor			Non-			Total
	LLC			Subsidiaries			Guarantor
							Subsidiaries
Net cash provided by operating activities	$	86.6		$	7.5		$	3		$	97.1
Cash flows from investing activities:
Purchases of property and equipment, net of stimulus grants	(80.5		)	(2.8		)	(3.4		)	(86.7		)
Acquisitions, net of cash acquired	—			(0.3		)	—			(0.3		)
Net cash used in investing activities	(80.5		)	(3.1		)	(3.4		)	(87.0		)
Cash flows from financing activities:
Equity contributions	0.6			—			—			0.6
Dividends received/(paid)	—			—			—			—
Principal repayments on long-term debt	(4.1		)	—			—			(4.1		)
(Payment of)/receipt from intercompany loan	—			—			—			—
Principal repayments on capital lease obligations	(0.3		)	(0.1		)	—			(0.4		)
Debt issuance costs, net of early redemption fees	(0.2		)	—			—			(0.2		)
Net cash used in financing activities	(4.0		)	(0.1		)	—			(4.1		)
Effect of changes in foreign exchange rates on cash	—			—			0.1			0.1
Net increase/(decrease) in cash and cash equivalents	2.1			4.3			(0.3		)	6.1
Cash and cash equivalents, beginning of period	86.8			1			3.5			91.3
Cash and cash equivalents, end of period	$	88.9		$	5.3		$	3.2		$	97.4

Subsequent_Events_Notes

Subsequent Events (Notes)	3 Months Ended
	Sep. 30, 2014
Subsequent Events [Abstract]	'
SUBSEQUENT EVENTS	'
	SUBSEQUENT EVENTS
	Restricted Stock Grant to Chief Executive Officer
	On September 17, 2014, the ZGH Compensation Committee approved a one-time grant of ZGH restricted stock units (“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 eighteen thousand dollars from $0.4. The grant was made on November 5, 2014. The units will vest based on the proposed new RSU vesting schedule associated with the ZGH compensation plan following the ZGH initial public offering. No other terms of Mr. Caruso’s employment agreement with the Company were modified.
	Distribution of Common Stock
	On October 9, 2014, ZGH and CII’s board of managers approved a non-liquidating distribution by CII of shares of ZGH common stock held by CII to holders of vested CII common units pursuant to the terms of the CII Operating Agreement. The total number of shares to be distributed to all CII common unit holders in connection with ZGH's initial public offering, or upon future distributions following resolution of contingent distributions among members of CII and upon the vesting of CII common units, is fixed at 223,000,000 shares of ZGH's common stock. The number of shares received by each CII common unit holder was dependent upon the actual public offering price for ZGH's initial public offering and the class of CII units held by such common unit holder, which dictated the applicable threshold for distributions. Employees and independent directors of the Company with vested CII common units received shares of ZGH common stock equal in value to the underlying value of their vested CII common units. Based on the offering price of $19.00, CII distributed 206,167,766 shares of ZGH's common stock to holders of CII preferred and common units immediately prior to the offering in respect of CII preferred and vested common units. Employees with unvested CII common units will continue to receive monthly distributions of ZGH common stock as they vest under the original terms of the CII common unit grant agreements in accordance with the CII operating agreement. In addition, CII will distribute additional shares of the ZGH's common stock to CII common unit holders on a quarterly basis through June 30, 2016 based on stock performance.
	In connection with the distribution, the Company adjusted the corresponding stock-based compensation liability to its fair value with an offsetting adjustment to stock-based compensation expense during the second quarter of Fiscal 2015. If the Company’s stock-based compensation liability as of September 30, 2014 were derived using a value for ZGH outstanding common shares based on $19.00 per share, the liability would be $475.7, representing a decrease of $38.5. Correspondingly, the fair value of unvested common units issued to employees and independent directors would be approximately $107.9.
	Initial Public Offering
	On October 22, 2014, the Company's parent, Holdings, completed an initial public offering of 24,079,002 shares of common stock at an offering price of $19.00 per share. Shares sold in the offering consisted of 16,008,679 shares sold by ZGH and 8,070,323 shares sold by selling stockholders (including CII investors and employees, former employees, and directors and officers of Holdings). The shares sold included the exercise of an option by the underwriters to purchase an additional 3,026,371 shares from selling shareholders. The underwriters’ option to purchase additional shares was exercised on October 20, 2014. ZGH's shares were listed on the New York Stock Exchange on October 17, 2014.

Business_and_Basis_of_Presenta1

Business and Basis of Presentation (Policy)	3 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Basis Of Presentation	'
	Basis of Presentation
	The accompanying condensed consolidated financial statements include all the accounts of the Company and its wholly-owned subsidiaries. All inter-company accounts and transactions have been eliminated in consolidation. The accompanying 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 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 month periods ended September 30, 2014 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 continuing operations and are presented in millions of dollars.
	The Company's fiscal year ends June 30 each year, and we refer to the fiscal year ended June 30, 2014 as “Fiscal 2014” and the fiscal year ending June 30, 2015 as “Fiscal 2015.”
Significant Accounting Policies	'
	Significant Accounting Policies
	There have been no changes to the Company's significant accounting policies described in its Annual Report.
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 disputed line cost billings, 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 fair values used to compute the stock-based compensation liability. 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.

Business_and_Basis_of_Presenta2

Business and Basis of Presentation (Tables)	3 Months Ended
	Sep. 30, 2014
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Schedule of Selling, General and Administrative Expenses	'
	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			48.9			47.8			53.3			192.8
	Transfer of Zayo Professional Services	2			1.9			1.8			3.3			9
	Operating costs, as adjusted	$	79.7		$	85.8		$	85		$	92.8		$	343.3
	Selling, general and administrative expenses, as originally stated	$	117.4		$	134.2		$	142.7		$	176.9		$	571.2
	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, as adjusted	$	76.4		$	87		$	96.6		$	124.6		$	384.6

Acquisitions_Tables

Acquisitions (Tables)	3 Months Ended
	Sep. 30, 2014
Business Combinations [Abstract]	'
Schedule of Acquisitions	'
	The table below reflects the Company's estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2015 acquisitions:
			AtlantaNAP				Neo
	Acquisition date		July 1, 2014				July 1, 2014
	Cash		$	—			$	4.2
	Other current assets		0.3				13.1
	Property and equipment		9.7				42.9
	Deferred tax assets, net		0.1				—
	Intangibles		30.4				13.4
	Goodwill		13.6				25
	Other assets		—				2.4
	Total assets acquired		54.1				101
	Current liabilities		1.3				10.3
	Deferred revenue		0.3				6.3
	Deferred tax liability, net		—				6.3
	Total liabilities assumed		1.6				22.9
	Net assets acquired		52.5				78.1
	Less cash acquired		—				(4.2		)
	Net consideration paid		$	52.5			$	73.9
	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		August 1, 2013				October 1, 2013			October 2, 2013		March 4, 2014		May 16, 2014
	Cash		$	0.1			$	1.2		$	—	$	—	$	13.7
	Other current assets		0.5				2.3			0.8		0.7		10.7
	Property and equipment		15.9				11.5			15.9		3		219.5
	Deferred tax assets, net		—				—			7.7		0.2		—
	Intangibles		0.2				18			19.3		10.1		61.2
	Goodwill		3				24			19.8		4.7		90.2
	Other assets		0.5				—			0.1		—		9.9
	Total assets acquired		20.2				57			63.6		18.7		405.2
	Current liabilities		0.7				1			1.3		0.6		16.9
	Deferred revenue		0.2				5.1			19.2		0.4		44.3
	Other liabilities		14.3				—			—		0.2		—
	Deferred tax liability, net		3				9.6			—		—		38
	Total liabilities assumed		18.2				15.7			20.5		1.2		99.2
	Net assets acquired		2				41.3			43.1		17.5		306
	Less cash acquired		(0.1		)		(1.2		)	—		—		(13.7		)
	Net consideration paid		$	1.9			$	40.1		$	43.1	$	17.5	$	292.3
Schedule Of Pro-Forma Financial Information (Unaudited)	'
	.
		Three months ended September 30,
		2014				2013
	Revenue	$	320.6			$	299
	Loss from operations	$	(110.3	)		$	(30.0	)
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 carryforwards	$	2.5
	Deferred revenue	4.4
	Total deferred income tax assets	6.9
	Deferred income tax liabilities:
	Property and equipment	(32.7		)
	Intangible assets	(12.2		)
	Total deferred income tax liabilities	(44.9		)
	Net deferred income tax liabilities	$	(38.0	)

SpinOff_Of_Business_Tables

Spin-Off Of Business (Tables)	3 Months Ended
	Sep. 30, 2014
Discontinued Operations and Disposal Groups [Abstract]	'
Schedule Of Earnings From Discontinued Operations	'

Goodwill_Tables

Goodwill (Tables)	3 Months Ended
	Sep. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule Of Goodwill	'
	The following rollforward reflects the allocation of goodwill acquired in the Company's Fiscal 2014 and 2015 acquisitions to the Company's reporting units:
		Dark Fiber			Waves			SONET		Ethernet			IP			MIG		zColo		Other		Total
	As of June 30, 2014	$	269.9		$	270		$	50.3	$	96.7		$	80.4		$	43.7	$	19.6	$	14.7	$	845.3
	Additions:
	AtlantaNAP	—			—			—		—			—			—		13.6		—		13.6
	Neo	—			—			—		—			—			—		—		23.2		23.2
	Foreign currency translation and other	(4.4		)	(3.4		)	—		(0.1		)	(0.1		)	—		0.2		—		(7.8		)
	As of September 30, 2014	$	265.5		$	266.6		$	50.3	$	96.6		$	80.3		$	43.7	$	33.4	$	37.9	$	874.3

Intangible_Assets_Tables

Intangible Assets (Tables)	3 Months Ended
	Sep. 30, 2014
Intangible Assets, Net (Excluding Goodwill) [Abstract]	'
Schedule Of Intangible Assets	'
	Identifiable acquisition-related intangible assets as of September 30, 2014 and June 30, 2014 were as follows:
		Gross		Accumulated			Net
		Carrying		Amortization
		Amount
	30-Sep-14
	Finite-Lived Intangible Assets
	Customer relationships	$	825	$	(113.2	)	$	711.8
	Trade names	0.1		—			0.1
	Underlying rights	1.7		(0.1		)	1.6
		826.8		(113.3		)	713.5
	Indefinite-Lived Intangible Assets
	Certifications	3.5		—			3.5
	Underlying rights	18.5		—			18.5
	Total	$	848.8	$	(113.3	)	$	735.5
	June 30, 2014
	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
		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)	3 Months Ended
	Sep. 30, 2014
Debt Disclosure [Abstract]	'
Schedule of Debt	'
	As of September 30, 2014 and June 30, 2014, long-term debt was as follows:
	(dollars in millions)	September 30,			June 30,
		2014			2014
	Term Loan Facility due 2019	$	2,005.70		$	2,010.80
	8.125% Senior Secured Notes due 2020	750			750
	10.125% Senior Unsecured Notes due 2020	500			500
	Total debt obligations	3,255.70			3,260.80
	Unamortized discount on Term Loan Facility due 2019	(19.7		)	(20.6		)
	Carrying value of debt	3,236.00			3,240.20
	Less current portion	(20.5		)	(20.5		)
	Long-term debt, less current portion	$	3,215.50		$	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)	3 Months Ended
	Sep. 30, 2014
Income Tax Disclosure [Abstract]	'
Schedule of Components of Income Tax Expense (Benefit)	'
	The Company’s provision/(benefit) for income taxes from continuing operations is summarized as follows:
		Three months ended September 30,
			2014				2013
	Current income taxes
	Federal		$	1.5			$	—
	State		0.9				0.8
	Foreign		0.8				—
	Total		3.2				0.8
	Deferred income taxes
	Federal		6.3				6.9
	State		0.2				0.2
	Foreign		(0.3		)		1.4
	Total		6.2				8.5
	Total provision for income taxes		$	9.4			$	9.3
Schedule of Income before Income Tax, Domestic and Foreign	'
	The United States and foreign components of income/(loss) from continuing operations before income taxes for the three months ended September 30, 2014 and 2013 are as follows:
		Three months ended September 30,
		2014				2013
	United States	$	(92.3	)		$	(22.6	)
	Foreign	(8.6		)		4.4
	Total	$	(100.9	)		$	(18.2	)
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-month periods ended September 30, 2014 and 2013 are as follows:
		For the three months ended September 30,
		(in millions)
		2014				2013
	Expected benefit at statutory rate	$	(35.3	)		$	(6.4	)
	Increase due to:
	Non-deductible stock-based compensation	47.3				17
	State income taxes benefit, net of federal benefit	(4.5		)		(1.1		)
	Transaction costs not deductible for tax purposes	0.2				0.2
	Foreign tax rate differential	1.1				(0.7		)
	Other, net	0.6				0.3
	Provision for income taxes	$	9.4			$	9.3

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Sep. 30, 2014
Share-based Compensation [Abstract]	'
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs	'
	The following table summarizes the Company’s stock-based compensation expense liability and equity classified awards included on the consolidated statements of operations.
		Three Months Ended September 30,
		2014		2013
	Included in:
	Operating costs	$	14.4	$	3.7
	Selling, general and administrative expenses	108.7		39.2
		$	123.1	$	42.9
Schedule Of Estimated Fair Value Of Common Units	'
	As of September 30, 2014 and June 30, 2014, the estimated fair value of the common units was as follows:
	Common Unit Class	September 30, 2014		June 30, 2014
		(estimated per unit value)
	Class A	$	2.97	$	2.47
	Class B	2.68		2.22
	Class C	2.31		1.92
	Class D	2.25		1.86
	Class E	1.95		1.62
	Class F	1.74		1.44
	Class G	0.99		0.82
	Class H	0.84		0.7
	Class I	0.54		0.45
	Class J	0.39		0.33
	Class K	0.34		0.29
	ZPS Class A	0.09		0.09
Common Unit Liquidation Thresholds By Stock Series	'
	Common unit holders of each of the following classes begin sharing in the proceeds of a liquidation event once the total amount distributed to earlier classes reaches the following liquidation thresholds:
	Common Unit Class	Liquidation Threshold
	Class A	$	—
	Class B	15
	Class C	40
	Class D	45
	Class E	75
	Class F	95
	Class G	235
	Class H	290
	Class I	435
	Class J	515
	Class K	545

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Sep. 30, 2014
Fair Value Disclosures [Abstract]	'
Schedule Of Financial Instruments Measured At Fair Value On A Recurring Basis	'
	The Company records its stock-based compensation liability at its estimated fair value. Financial instruments measured at fair value on a recurring basis are summarized below:
		Level	30-Sep-14		30-Jun-14
	Liabilities Recorded at Fair Value in the Financial Statements:
	Interest rate swap	Level 2	$	—	$	2
	Stock-based compensation liability	Level 3	$	514.2	$	392.4

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	3 Months Ended
	Sep. 30, 2014
Related Party Transaction, Due from (to) Related Party [Abstract]	'
Schedule Of Transactions Recognized With Related Parties	'
	The following table represents the revenue and expense transactions we recognized with Onvoy for the periods presented:
		Three Months Ended September 30,
		2014			2013
	Revenues	$	1.7		1.7
	Operating costs	$	(0.3	)	(0.4	)

Segment_Reporting_Tables

Segment Reporting (Tables)	3 Months Ended
	Sep. 30, 2014
Segment Reporting [Abstract]	'
Summary Of Significant Financial Information	'
		As of and for the three months ended September 30, 2014
		Physical Infrastructure			Lit Services			Other			Corp/		Total
											elimination
	Revenue from external customers	$	149.7		$	156.1		$	14.8		$	—	$	320.6
	Segment Adjusted EBITDA	$	97.3		$	82.2		$	3.5		$	—	$	183
	Total assets	$	2,869.50		$	1,772.60		$	131.8		$	284.6	$	5,058.50
	Capital expenditures	$	(68.0	)	$	(46.1	)	$	(1.2	)	$	—	$	(115.3	)
		As of and for the three months ended September 30, 2013
		Physical Infrastructure			Lit Services			Other			Corp/		Total
											elimination
	Revenue from external customers	$	113.6		$	149.4		$	6.7		$	—	$	269.7
	Segment Adjusted EBITDA	$	74.4		$	80.9		$	1.9		$	—	$	157.2
	Capital expenditures	$	(45.2	)	$	(41.5	)	$	—		$	—	$	(86.7	)
		As of June 30, 2014
		Physical Infrastructure			Lit Services			Other			Corp/		Total
											elimination
	Total assets	$	2,851.80		$	1,739.10		$	43.1		$	415.3	$	5,049.30
Reconciliation from net earnings/(loss) to Adjusted EBITDA	'
	Reconciliation Total Segment Adjusted EBITDA to from net earnings/(loss) from continuing operations
		Three months ended September 30,
		2014			2013
	Segment Adjusted EBITDA	$	183		$	157.2
	Interest expense	(46.9		)	(51.5		)
	Provision for income taxes	(9.4		)	(9.3		)
	Depreciation and amortization expense	(96.0		)	(81.0		)
	Transaction costs	(3.2		)	(0.6		)
	Stock-based compensation	(123.1		)	(42.9		)
	Foreign currency loss/(gain) on intercompany loans	(14.7		)	0.6
	Net loss from continuing operations	$	(110.3	)	$	(27.5	)

Condensed_Consolidating_Financ1

Condensed Consolidating Financial Information (Tables)	3 Months Ended
	Sep. 30, 2014																Jun. 30, 2014
Condensed Consolidating Financial Information [Abstract]	'																'
Schedule Of Condensed Consolidating Balance Sheet	'																'
																	Condensed Consolidating Balance Sheets (Unaudited)
																	September 30, 2014
																		Zayo Group,			Guarantor		Non-			Eliminations			Total
																		LLC			Subsidiaries		Guarantor
																							Subsidiaries
																		(Issuer)
																	Assets
																	Current assets
																	Cash and cash equivalents	$	146.1		$	1	$	20.2		$	—		$	167.3
																	Trade receivables, net	31.6			6.9		26			—			64.5
																	Due from related parties	2.4			—		1.1			(1.0		)	2.5
																	Prepaid expenses	19.2			3.1		6.5			—			28.8
																	Deferred income taxes	158.9			—		1.4			—			160.3
																	Other assets	1.5			—		1.4			—			2.9
																	Total current assets	359.7			11		56.6			(1.0		)	426.3
																	Property and equipment, net	2,438.20			111.6		345.9			—			2,895.70
																	Intangible assets, net	574.9			58.5		102.1			—			735.5
																	Goodwill	682.4			31.7		160.2			—			874.3
																	Debt issuance costs, net	85.6			—		—			—			85.6
																	Other assets	24.5			4.2		12.4			—			41.1
																	Related party receivable, long-term	301.5			—		—			(301.5		)	—
																	Investment in subsidiary	360.3			—		—			(360.3		)	—
																	Total assets	$	4,827.10		$	217	$	677.2		$	(662.8	)	$	5,058.50
																	Liabilities and member’s equity
																	Current liabilities
																	Current portion of long-term debt	$	20.5		$	—	$	—		$	—		$	20.5
																	Accounts payable	20.7			2.2		5.6			—			28.5
																	Accrued liabilities	128.9			7.8		24.2			—			160.9
																	Accrued interest	26			—		—			—			26
																	Capital lease obligations, current	1.6			1.5		—			—			3.1
																	Due to related parties	—			—		1			(1.0		)	—
																	Deferred revenue, current	59.8			1.5		31.4			—			92.7
																	Total current liabilities	257.5			13		62.2			(1.0		)	331.7
																	Long-term debt, non-current	3,215.50			—		—			—			3,215.50
																	Related party debt, long-term	—			—		301.5			(301.5		)	—
																	Capital lease obligations, non-current	5.6			16.1		1.6			—			23.3
																	Deferred revenue, non-current	483.5			4		25.1			—			512.6
																	Stock-based compensation liability	452.4			28.5		33.3			—			514.2
																	Deferred income taxes, net	112.9			—		49.1			—			162
																	Other long-term liabilities	10.1			10.1		0.2			—			20.4
																	Total liabilities	4,537.50			71.7		473			(302.5		)	4,779.70
																	Member’s equity
																	Member’s interest	776.6			104		215.8			(367.4		)	729
																	Accumulated other comprehensive income	—			—		2.1			—			2.1
																	(Accumulated deficit)/retained earnings	(487.0		)	41.3		(13.7		)	7.1			(452.3		)
																	Total member’s equity	289.6			145.3		204.2			(360.3		)	278.8
																	Total liabilities and member’s equity	$	4,827.10		$	217	$	677.2		$	(662.8	)	$	5,058.50
																	Condensed Consolidating Balance Sheets (Unaudited)
																	June 30, 2014
																		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
Deferred income taxes, net	—			—		—			—			—
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
Deferred revenue, non-current	459.5			4		33.4			—			496.9
Deferred income taxes, net	345			22.2		25.2			—			151.8
Stock-based compensation liability	106.5			—		45.3			—			392.4
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 September 30, 2014
		Zayo Group,			Guarantor			Non-			Eliminations			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
		(Issuer)
	Revenue	$	257.2		$	24.8		$	38.6		$	—		$	320.6
	Operating costs and expenses
	Operating costs (excluding depreciation and amortization)	88			7.6			11.7			—			107.3
	Selling, general and administrative expenses	126.9			10.7			19			—			156.6
	Depreciation and amortization	80			4.5			11.5			—			96
	Total operating costs and expenses	294.9			22.8			42.2			—			359.9
	Operating income	(37.7		)	2			(3.6		)	—			(39.3		)
	Other expenses
	Interest expense	(42.4		)	(0.1		)	(4.4		)	—			(46.9		)
	Other income, net	(14.1		)	—			(0.6		)	—			(14.7		)
	Equity in net earnings of subsidiaries	(7.1		)	—			—			7.1			—
	Total other (expense)/income, net	(63.6		)	(0.1		)	(5.0		)	7.1			(61.6		)
	(Loss)/earnings before provision for income taxes	(101.3		)	1.9			(8.6		)	7.1			(100.9		)
	Provision for income taxes	9			—			0.4			—			9.4
	Net (loss)/earnings	$	(110.3	)	$	1.9		$	(9.0	)	$	7.1		$	(110.3	)
	Condensed Consolidating Statements of Operations (Unaudited)
	For the three months ended September 30, 2013
		Zayo Group,			Guarantor			Other Non-			Eliminations			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
		(Issuer)
	Revenue	$	238.8		$	16.1		$	14.8		$	—		$	269.7
	Operating costs and expenses
	Operating costs (excluding depreciation and amortization)	70.6			5.7			3.4			—			79.7
	Selling, general and administrative expenses	66.5			5.6			4.3			—			76.4
	Depreciation and amortization	75.4			2.3			3.3			—			81
	Total operating costs and expenses	212.5			13.6			11			—			237.1
	Operating income	26.3			2.5			3.8			—			32.6
	Other expenses
	Interest expense	(49.2		)	(2.2		)	(0.1		)	—			(51.5		)
	Other income, net	—			—			0.7			—			0.7
	Equity in net earnings of subsidiaries	3.3			—			—			(3.3		)	—
	Total other (expense)/income, net	(45.9		)	(2.2		)	0.6			(3.3		)	(50.8		)
	(Loss)/earnings before provision for income taxes	(19.6		)	0.3			4.4			(3.3		)	(18.2		)
	Provision for income taxes	7.8			—			1.5			—			9.3
	Net (loss)/earnings	$	(27.4	)	$	0.3		$	2.9		$	(3.3	)	$	(27.5	)
Schedule Of Condensed Consolidating Statements Of Cash Flows	'																'
	Condensed Consolidating Statements of Cash Flows (Unaudited)
	For the three months ended September 30, 2014
		Zayo Group,			Guarantor			Non-			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
		(Issuer)
	Net cash provided by operating activities	$	102.3		$	9		$	6.9		$	118.2
	Cash flows from investing activities:
	Purchases of property and equipment	(98.5		)	(10.7		)	(6.1		)	(115.3		)
	Acquisitions, net of cash acquired	(0.1		)	(52.5		)	(73.9		)	(126.5		)
	Net cash used in investing activities	(98.6		)	(63.2		)	(80.0		)	(241.8		)
	Cash flows from financing activities:
	Equity contributions/(distributions)	(69.6		)	54.6			15			—
	Dividend received/(paid)	—			—			—			—
	Principal repayments on long-term debt	(5.1		)	—			—			(5.1		)
	(Payment of)/receipt from intercompany loan	(43.4		)	—			43.4			—
	Principal repayments on capital lease obligations	(0.3		)	(0.4		)	—			(0.7		)
	Net cash (used in)/provided by financing activities	(118.4		)	54.2			58.4			(5.8		)
	Effect of changes in foreign exchange rates on cash	—			—			(0.7		)	(0.7		)
	Net decrease in cash and cash equivalents	(114.7		)	—			(15.4		)	(130.1		)
	Cash and cash equivalents, beginning of period	260.8			1			35.6			297.4
	Cash and cash equivalents, end of period	$	146.1		$	1		$	20.2		$	167.3
	Condensed Consolidating Statements of Cash Flows (Unaudited)
	For the three months ended September 30, 2013
		Zayo Group,			Guarantor			Non-			Total
		LLC			Subsidiaries			Guarantor
								Subsidiaries
	Net cash provided by operating activities	$	86.6		$	7.5		$	3		$	97.1
	Cash flows from investing activities:
	Purchases of property and equipment, net of stimulus grants	(80.5		)	(2.8		)	(3.4		)	(86.7		)
	Acquisitions, net of cash acquired	—			(0.3		)	—			(0.3		)
	Net cash used in investing activities	(80.5		)	(3.1		)	(3.4		)	(87.0		)
	Cash flows from financing activities:
	Equity contributions	0.6			—			—			0.6
	Dividends received/(paid)	—			—			—			—
	Principal repayments on long-term debt	(4.1		)	—			—			(4.1		)
	(Payment of)/receipt from intercompany loan	—			—			—			—
	Principal repayments on capital lease obligations	(0.3		)	(0.1		)	—			(0.4		)
	Debt issuance costs, net of early redemption fees	(0.2		)	—			—			(0.2		)
	Net cash used in financing activities	(4.0		)	(0.1		)	—			(4.1		)
	Effect of changes in foreign exchange rates on cash	—			—			0.1			0.1
	Net increase/(decrease) in cash and cash equivalents	2.1			4.3			(0.3		)	6.1
	Cash and cash equivalents, beginning of period	86.8			1			3.5			91.3
	Cash and cash equivalents, end of period	$	88.9		$	5.3		$	3.2		$	97.4

Business_and_Basis_of_Presenta3

Business and Basis of Presentation (Details) (USD $)	3 Months Ended					12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2014
Operating costs, excluding depreciation and amortization	$107,300,000	$92,800,000	$85,000,000	$85,800,000	$79,700,000	$343,300,000
Transfer of Zayo Professional Services	2,000,000	3,300,000	1,800,000	1,900,000	'	9,000,000
Selling, general and administrative expenses	156,600,000	124,600,000	96,600,000	87,000,000	76,400,000	384,600,000
Transfer of Zayo Professional Services	1,800,000	1,000,000	1,700,000	1,700,000	'	6,200,000
Scenario, Previously Reported [Member]	'	'	'	'	'	'
Operating costs, excluding depreciation and amortization	34,900,000	36,200,000	35,400,000	35,000,000	'	141,500,000
Selling, general and administrative expenses	117,400,000	176,900,000	142,700,000	134,200,000	'	571,200,000
Restatement Adjustment [Member]	'	'	'	'	'	'
Operating costs, excluding depreciation and amortization	42,800,000	53,300,000	47,800,000	48,900,000	'	192,800,000
Selling, general and administrative expenses	($42,800,000)	($53,300,000)	($47,800,000)	($48,900,000)	'	($192,800,000)

Acquisitions_Narrative_Details

Acquisitions (Narrative) (Details)

0 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

82 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

Jul. 02, 2014

Sep. 30, 2014

Sep. 30, 2013

Mar. 31, 2013

Jun. 30, 2014

Mar. 31, 2014

Aug. 01, 2013

31-May-13

Sep. 30, 2014

Sep. 30, 2013

Jul. 01, 2014

Aug. 01, 2013

Oct. 02, 2013

31-May-13

Sep. 30, 2014

Sep. 30, 2013

Oct. 02, 2014

Oct. 02, 2013

Sep. 30, 2014

Oct. 02, 2013

31-May-13

Sep. 30, 2014

Oct. 02, 2013

Sep. 30, 2014

Mar. 04, 2014

Sep. 30, 2014

Mar. 04, 2014

Jul. 02, 2014

Jul. 02, 2014

Jul. 01, 2014

Jul. 02, 2014

Jul. 01, 2014

Jul. 02, 2014

Jul. 02, 2014

Sep. 30, 2014

Sep. 30, 2013

Jul. 01, 2014

Jul. 02, 2014

Dec. 14, 2012

Sep. 30, 2014

16-May-14

16-May-14

Mar. 04, 2014

Jul. 02, 2014

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

business_combination

Colocation Asset Purchase [Member]

Colocation Asset Purchase [Member]

Colocation Asset Purchase [Member]

Colocation Asset Purchase [Member]

Colocation Asset Purchase [Member]

Colocation Asset Purchase [Member]

Access [Member]

Access [Member]

Access [Member]

Access [Member]

Access [Member]

Access [Member]

Access [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

AtlantaNAP [Member]

AtlantaNAP [Member]

AtlantaNAP [Member]

AtlantaNAP [Member]

AtlantaNAP [Member]

First Telecom [Member]

360networks [Member]

Geo Networks Limited [Member]

Geo Networks Limited [Member]

Geo Networks Limited [Member]

Euro Member Countries, Euro

USD ($)

USD ($)

USD ($)

USD ($)

Subsequent Event [Member]

Customer relationships [Member]

USD ($)

USD ($)

USD ($)

USD ($)

Subsequent Event [Member]

Customer relationships [Member]

Customer relationships [Member]

USD ($)

USD ($)

USD ($)

Customer relationships [Member]

Customer relationships [Member]

USD ($)

USD ($)

Customer relationships [Member]

USD ($)

EUR (€)

USD ($)

Subsequent Event [Member]

Subsequent Event [Member]

Customer relationships [Member]

USD ($)

USD ($)

USD ($)

USD ($)

Customer relationships [Member]

Customer relationships [Member]

USD ($)

USD ($)

GBP (£)

USD ($)

Neo Telecoms [Member]

USD ($)

USD ($)

USD ($)

USD ($)

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair value

'

'

'

'

'

'

$200,000

'

'

'

'

'

$18,000,000

'

'

'

'

'

'

$19,300,000

'

'

'

'

$10,100,000

'

'

'

'

$13,400,000

'

'

'

'

'

'

$30,400,000

'

'

'

$61,200,000

'

'

'

Acquired Finite-lived Intangible Assets, Weighted Average Useful Life

'

'

'

'

'

'

'

'

'

'

'

'12 years

'

'

'

'

'

'20 years

'

'

'

'

'18 years

'

'

'

'11 years

'

'

'

'

'

'15 years

'

'

'

'

'11 years

'

'

'9 years 8 months 12 days

'9 years 8 months 12 days

'

'

Deferred revenue

'

'

'

'

'

'

200,000

'

'

'

'

'

5,100,000

'

'

'

'

'

'

19,200,000

'

'

'

'

400,000

'

'

'

'

6,300,000

'

'

'

'

'

'

300,000

'

'

'

44,300,000

'

'

'

Property Plant and Equipment Purchase Accounting Adjustments

'

3,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

9,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Finite-Lived Intangible Assets, Purchase Accounting Adjustments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,000,000

'

'

'

'

2,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Deferred Revenue Purchase Accounting Adjustments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,000,000

'

'

'

'

'

'

700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Increase in goodwill

'

-15,800,000

'

'

-27,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

13,600,000

'

'

'

23,200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of business combinations

'

'

'

'

'

32

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Acquisition date

'

'

'

'

'

'

1-Aug-13

'

'

'

'

'

1-Oct-13

'

'

'

'

'

'

2-Oct-13

'

'

'

'

4-Mar-14

'

'

1-Jul-14

1-Jul-14

'

'

'

'

1-Jul-14

'

'

'

'

'

'

'

'

16-May-14

'

Business acquisition purchase price

'

'

'

'

'

'

1,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of shares issued for acquisition

'

'

'

'

'

'

301,949

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of shares issued for acquisition

'

'

'

'

'

'

1,637,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash consideration

'

'

'

'

'

'

300,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cash consideration, net of cash acquired

100,000

126,500,000

300,000

'

'

'

300,000

1,900,000

0

300,000

'

'

'

40,100,000

100,000

0

40,100,000

'

'

'

43,100,000

'

'

'

17,500,000

'

'

73,900,000

57,200,000

'

'

'

'

52,500,000

-52,500,000

0

'

'

'

'

292,300,000

174,300,000

292,300,000

'

Purchase price, held in escrow

'

'

'

'

'

'

'

'

'

'

'

'

4,000,000

'

'

'

'

'

'

'

'

'

'

'

1,775,000

'

'

'

'

'

'

'

'

5,250,000

'

'

'

'

'

'

'

'

'

'

Business Acquisition, Cost Of Acquired Entity, Portion Of Purchase Price Held In Escrow Allocated To Selling General And Administrative Expense

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3,781,000

'

'

'

'

Percentage of company acquired

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

'

'

'

'

'

'

0.00%

'

'

'

'

100.00%

'

'

'

'

4.00%

4.00%

96.00%

'

'

'

'

100.00%

'

'

'

100.00%

100.00%

'

'

Business Combination, Consideration Transferred, Amount Held in Escrow

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

11,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

8,700,000

Estimated useful life of acquired customer relationships

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'18 years

'

'

'

'

'

Acquisition-related costs

'

3,249,000

'

587,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Preliminary purchase price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

43,137,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notes Payable, Related Parties

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

69,100,000

113,400,000

'

'

Deferred Tax Assets, Net

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

($38,000,000)

'

'

'

Acquisitions_Schedule_Of_Acqui

Acquisitions (Schedule Of Acquisition) (Details)

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

In Thousands, unless otherwise specified

Jul. 02, 2014

Sep. 30, 2014

Sep. 30, 2013

Jun. 30, 2014

Aug. 01, 2013

31-May-13

Sep. 30, 2014

Sep. 30, 2013

Jul. 02, 2014

Jul. 02, 2014

Jul. 01, 2014

Jul. 02, 2014

Sep. 30, 2014

Sep. 30, 2013

Jul. 01, 2014

Oct. 02, 2013

31-May-13

Sep. 30, 2014

Sep. 30, 2013

Oct. 02, 2013

31-May-13

Mar. 04, 2014

16-May-14

16-May-14

Mar. 04, 2014

USD ($)

USD ($)

USD ($)

USD ($)

Colocation Asset Purchase [Member]

Colocation Asset Purchase [Member]

Colocation Asset Purchase [Member]

Colocation Asset Purchase [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

AtlantaNAP [Member]

AtlantaNAP [Member]

AtlantaNAP [Member]

AtlantaNAP [Member]

Access [Member]

Access [Member]

Access [Member]

Access [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

CoreXchange [Member]

Geo Networks Limited [Member]

Geo Networks Limited [Member]

Geo Networks Limited [Member]

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

EUR (€)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

GBP (£)

USD ($)

Business Acquisition [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Acquisition date

'

'

'

'

1-Aug-13

'

'

'

1-Jul-14

1-Jul-14

'

1-Jul-14

'

'

'

1-Oct-13

'

'

'

2-Oct-13

'

4-Mar-14

'

'

16-May-14

Cash

'

'

'

'

($100)

'

'

'

'

'

($4,200)

'

'

'

$0

($1,200)

'

'

'

$0

'

$0

($13,700)

'

'

Other current assets

'

'

'

'

500

'

'

'

'

'

13,100

'

'

'

300

2,300

'

'

'

800

'

700

10,700

'

'

Property and equipment

'

'

'

'

15,900

'

'

'

'

'

42,900

'

'

'

9,700

11,500

'

'

'

15,900

'

3,000

219,500

'

'

Deferred tax assets, net

'

'

'

'

0

'

'

'

'

'

0

'

'

'

100

0

'

'

'

7,700

'

200

0

'

'

Intangibles

'

'

'

'

200

'

'

'

'

'

13,400

'

'

'

30,400

18,000

'

'

'

19,300

'

10,100

61,200

'

'

Goodwill

'

874,300

'

845,300

3,000

'

'

'

'

'

25,000

'

'

'

13,600

24,000

'

'

'

19,800

'

4,700

90,200

'

'

Other assets

'

'

'

'

500

'

'

'

'

'

2,400

'

'

'

0

0

'

'

'

100

'

0

9,900

'

'

Total assets acquired

'

'

'

'

20,200

'

'

'

'

'

101,000

'

'

'

54,100

57,000

'

'

'

63,600

'

18,700

405,200

'

'

Current liabilities

'

'

'

'

700

'

'

'

'

'

10,300

'

'

'

1,300

1,000

'

'

'

1,300

'

600

16,900

'

'

Deferred revenue

'

'

'

'

200

'

'

'

'

'

6,300

'

'

'

300

5,100

'

'

'

19,200

'

400

44,300

'

'

Other liabilities

'

'

'

'

14,300

'

'

'

'

'

'

'

'

'

'

0

'

'

'

0

'

200

0

'

'

Deferred tax liability, net

'

'

'

'

3,000

'

'

'

'

'

6,300

'

'

'

0

9,600

'

'

'

0

'

0

38,000

'

'

Total liabilities assumed

'

'

'

'

18,200

'

'

'

'

'

22,900

'

'

'

1,600

15,700

'

'

'

20,500

'

1,200

99,200

'

'

Net assets acquired

'

'

'

'

2,000

'

'

'

'

'

78,100

'

'

'

52,500

41,300

'

'

'

43,100

'

17,500

306,000

'

'

Cash

'

'

'

'

-100

'

'

'

'

'

-4,200

'

'

'

0

-1,200

'

'

'

0

'

0

-13,700

'

'

Net cash paid

$100

$126,500

$300

'

$300

$1,900

$0

$300

$73,900

€ 57,200

'

$52,500

($52,500)

$0

'

'

$40,100

$100

$0

'

$43,100

$17,500

$292,300

£ 174,300

$292,300

Acquisitions_Schedule_of_Defer

Acquisitions (Schedule of Deferred Tax Assets and Liabilities) (Details) (USD $)	Sep. 30, 2014	Jun. 30, 2014	16-May-14
			Geo Networks Limited [Member]
Business Acquisition [Line Items]	'	'	'
Net operating loss carryforwards	'	'	$2,500,000
Deferred revenue	'	'	4,400,000
Total deferred income tax assets	'	'	6,900,000
Property and equipment	'	'	-32,700,000
Intangible assets	'	'	-12,200,000
Total deferred income tax liabilities	162,000,000	151,800,000	44,900,000
Net deferred income tax liabilities	'	'	($38,000,000)

Acquisitions_Schedule_Of_ProFo

Acquisitions (Schedule Of Pro-Forma Financial Information) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Business Combinations [Abstract]	'	'
Revenue	$320,600	$299,000
Loss from continuing operations	($110,300)	($30,000)

Goodwill_Narrative_Details

Goodwill (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014
Goodwill and Intangible Assets Disclosure [Abstract]	'	'
Goodwill	$874,300,000	$845,300,000
Foreign currency translation	6,700,000	'
Decrease to goodwill acquired	1,100,000	'
Goodwill, Period Increase (Decrease)	$15,800,000	$27,500,000

Goodwill_Schedule_Of_Goodwill_

Goodwill (Schedule Of Goodwill) (Details) (USD $)

3 Months Ended

12 Months Ended

3 Months Ended

3 Months Ended

3 Months Ended

Sep. 30, 2014

Jun. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Oct. 02, 2013

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Mar. 04, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Aug. 01, 2013

Oct. 02, 2013

Dark Fiber [Member]

Waves [Member]

Sonet [Member]

Ethernet [Member]

IP [Member]

MIG [Member]

zColo [Member]

Other Entity [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

Fiberlink, LLC [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

Colocation Asset Purchase [Member]

Access [Member]

Dark Fiber [Member]

Waves [Member]

Sonet [Member]

Ethernet [Member]

IP [Member]

MIG [Member]

zColo [Member]

Other Entity [Member]

Dark Fiber [Member]

Waves [Member]

Sonet [Member]

Ethernet [Member]

IP [Member]

MIG [Member]

zColo [Member]

Other Entity [Member]

Goodwill, beginning Balance

$845,300,000

'

$43,700,000

$269,900,000

$270,000,000

$50,300,000

$96,700,000

$80,400,000

$19,600,000

$14,700,000

'

$19,800,000

'

'

'

'

'

'

'

'

'

$4,700,000

'

'

'

'

'

'

'

'

$3,000,000

$24,000,000

Additions

-15,800,000

-27,500,000

'

'

'

'

'

'

'

'

13,600,000

'

0

0

0

0

0

0

13,600,000

0

23,200,000

'

0

0

0

0

0

0

0

23,200,000

'

'

Foreign currency translation

6,700,000

'

0

-4,400,000

-3,400,000

0

-100,000

-100,000

200,000

0

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Goodwill, Translation and Purchase Accounting Adjustments

-7,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Goodwill, ending balance

$874,300,000

$845,300,000

$43,700,000

$265,500,000

$266,600,000

$50,300,000

$96,600,000

$80,300,000

$33,400,000

$37,900,000

'

$19,800,000

'

'

'

'

'

'

'

'

'

$4,700,000

'

'

'

'

'

'

'

'

$3,000,000

$24,000,000

Intangible_Assets_Schedule_Of_

Intangible Assets (Schedule Of Intangible Assets) (Details) (USD $)	Sep. 30, 2014	Jun. 30, 2014
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross	$826,800	$791,100
Accumulated Amortization	-113,300	-104,300
Finite-Lived Intangible Assets, Net	713,500	686,800
Total Gross Carrying Amount	848,800	814,000
Intangible assets, net	735,500	709,700
Customer relationships [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross	825,000	789,200
Accumulated Amortization	-113,200	-104,200
Finite-Lived Intangible Assets, Net	711,800	685,000
Tradenames [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross	100	100
Accumulated Amortization	0	0
Finite-Lived Intangible Assets, Net	100	100
Underlying rights [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Finite-Lived Intangible Assets, Gross	1,700	1,800
Accumulated Amortization	-100	-100
Finite-Lived Intangible Assets, Net	1,600	1,700
Indefinite-Lived Intangible Assets	18,500	19,400
Certifications [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Indefinite-Lived Intangible Assets	$3,500	$3,500

LongTerm_Debt_Schedule_of_Long

Long-Term Debt (Schedule of Long-Term Debt) (Details) (USD $)	0 Months Ended
In Thousands, unless otherwise specified	Jul. 02, 2012	Sep. 30, 2014	Jun. 30, 2014
Debt Instrument [Line Items]	'	'	'
Line of Credit Facility, Commitment Fee Percentage	1.00%	'	'
Long-term Debt, Gross	'	$3,255,700	$3,260,800
Unamortized discount on Term Loan Facility due 2019	30,000	-19,700	-20,600
Carrying value of debt	'	3,236,000	3,240,200
Less current portion	'	-20,500	-20,500
Long-term debt, less current portion	'	3,215,500	3,219,700
Line of Credit Facility, Commitment Fee Amount	'0.0025	'	'
Line of Credit [Member] | Term Loan [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Long-term Debt, Gross	'	2,005,700	2,010,800
Secured Debt [Member] | Senior Secured Notes [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Long-term Debt, Gross	750,000	750,000	750,000
Unsecured Debt [Member] | Senior Unsecured Notes [Member]	'	'	'
Debt Instrument [Line Items]	'	'	'
Long-term Debt, Gross	$500,000	$500,000	$500,000

LongTerm_Debt_Narrative_Detail

Long-Term Debt (Narrative) (Details) (USD $)

0 Months Ended

3 Months Ended

0 Months Ended

0 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

0 Months Ended

3 Months Ended

Nov. 26, 2013

Jul. 02, 2012

Sep. 30, 2014

Mar. 31, 2014

Sep. 30, 2013

Jun. 30, 2014

Nov. 26, 2013

16-May-14

Oct. 05, 2012

Oct. 05, 2012

Jul. 02, 2012

Jul. 02, 2012

Oct. 05, 2012

Jun. 30, 2014

Aug. 13, 2012

Sep. 30, 2014

Sep. 30, 2013

Jun. 30, 2014

16-May-14

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2014

Jun. 30, 2014

16-May-14

16-May-14

Sep. 30, 2014

Jun. 30, 2014

Sixth Amendment [Member]

Term Loan [Member]

Term Loan [Member]

Senior Secured Notes [Member]

Senior Unsecured Notes [Member]

Revolver [Member]

Term Loan [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

Interest Rate Swap [Member]

LIBOR [Member]

LIBOR [Member]

LIBOR [Member]

LIBOR [Member]

Debt Instrument, Redemption, Period One [Member]

Term Loan [Member]

Term Loan [Member]

Term Loan [Member]

Term Loan [Member]

Term Loan [Member]

Term Loan [Member]

Fourth Amendment [Member]

Fourth Amendment [Member]

Fourth Amendment [Member]

Revolver [Member]

Term Loan [Member]

Term Loan [Member]

Senior Unsecured Notes [Member]

Line of Credit [Member]

Line of Credit [Member]

LIBOR [Member]

LIBOR [Member]

Minimum [Member]

Fifth Amendment [Member]

Minimum [Member]

Fifth Amendment [Member]

Line of Credit [Member]

Line of Credit [Member]

Minimum [Member]

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt instrument, interest rate

'

'

'

'

'

'

'

'

'

'

0.00%

10.13%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Discount on debt

'

$30,000,000

($19,700,000)

'

'

($20,600,000)

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Effective interest rate

'

'

3.00%

'

'

3.00%

'

'

'

'

'

'

'

4.50%

'

'

'

'

'

'

'

'

'

4.00%

4.00%

'

'

'

'

Loss on extinguishment of debt

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Payments of Debt Extinguishment Costs

'

'

'

'

200,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Percentage over variable rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.00%

2.80%

1.00%

3.00%

'

'

'

3.00%

1.00%

3.00%

'

Extinguishment of Debt, Gain (Loss), Net of Tax

'

'

'

1,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest rate decrease

'

'

'

'

'

'

'

'

0.50%

0.25%

'

'

0.50%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Floor rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.00%

'

Carrying value of the notes

'

'

3,255,700,000

'

'

3,260,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2,005,700,000

2,010,800,000

'

'

1,985,958,000

1,990,200,000

Payment towards principal

'

5,100,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Increase (Decrease), Net

150,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Maximum Borrowing Capacity

'

'

'

'

'

'

1,749,800,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt

'

'

3,236,000,000

'

'

3,240,200,000

'

2,015,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Outstanding letters of credit

'

'

6,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Available borrowing capacity

'

250,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest rate during period

'

2.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Redemption price

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100.00%

'

'

'

'

'

'

Debt issuance cost

1,500,000

'

'

'

'

'

'

3.2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Issuance Cost Expense (non-cash)

'

'

'

'

'

'

1,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Unamortized debt issuance cost

'

114,800,000

85,627,000

'

'

89,380,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Accretion of premium on debt

'

'

'

'

29,170,000

25,416,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Interest expense associated with the amortization of debt issuance costs

'

'

3,754,000

'

3,400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Notional amount of derivative

'

'

'

'

'

'

'

'

'

'

'

'

'

'

750,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

-1,977,000

2,264,000

'

'

'

'

'

'

'

'

'

'

'

'

Interest Rate Derivative Assets, at Fair Value

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

100,000

2,014,000

'

'

'

'

'

'

'

'

'

'

'

Proceeds from Issuance of Debt

'

'

'

'

'

'

'

275,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Call Feature

'

'

'

'

'

'

'

'0.995

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Line of Credit

'

'

$243,600,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Commitment Fee Percentage

'

1.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Interest Rate Description

'

'0.03

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

LongTerm_Debt_Debt_Covenants_D

Long-Term Debt (Debt Covenants) (Details)	Sep. 30, 2014
Fiscal Quarter Ending September 30, 2014 [Member]	'
Schedule of Debt Covenants [Line Items]	'
Fixed-Charge Coverage Ratio	2
Fiscal Quarter Ending December 31, 2014 [Member]	'
Schedule of Debt Covenants [Line Items]	'
Fixed-Charge Coverage Ratio	2
Fiscal Quarter Ending March 31, 2015 [Member]	'
Schedule of Debt Covenants [Line Items]	'
Fixed-Charge Coverage Ratio	2
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 30, 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	2.5
Fiscal Quarter Ending June 30, 2016 [Member]	'
Schedule of Debt Covenants [Line Items]	'
Fixed-Charge Coverage Ratio	2.25
Fiscal Quarter Ending September 30, 2016 [Member]	'
Schedule of Debt Covenants [Line Items]	'
Fixed-Charge Coverage Ratio	2.25
Fiscal Quarter Ending December 31, 2016 and thereafter [Member]	'
Schedule of Debt Covenants [Line Items]	'
Fixed-Charge Coverage Ratio	2.75

Income_Taxes_ProvisionBenefit_

Income Taxes (Provision/(Benefit) for Income Taxes) (Details) (USD $)	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Current income taxes	'	'
Federal	$1,500,000	$0
State	900,000	800,000
Foreign	800,000	0
Total	3,200,000	800,000
Deferred income taxes	'	'
Federal	6,300,000	6,900,000
State	200,000	200,000
Foreign	-300,000	1,400,000
Total	6,200,000	8,500,000
Provision/(benefit) for income taxes	$9,400,000	$9,300,000

Income_Taxes_Domestic_and_Fore

Income Taxes (Domestic and Foreign Components of Income (Loss) (Details) (USD $)	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'	'
United States	($92,300,000)	($22,600,000)
Foreign	-8,600,000	4,400,000
Loss from continuing operations before provision for income taxes	($100,900,000)	($18,200,000)

Income_Taxes_Schedule_Of_Recon

Income Taxes (Schedule Of Reconciliation Of Income Tax Provision) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'	'
Expected (benefit)/provision at statutory rate	($35,300)	($6,400)
Non-deductible stock-based compensation	47,300	17,000
State income taxes provision/(benefit), net of federal benefit	-4,500	-1,100
Transactions costs not deductible for tax purposes	200	200
Foreign tax rate differential	1,100	-700
Other, net	600	300
Provision/(benefit) for income taxes	$9,400	$9,300

Equity_Details

Equity (Details) (Colocation Asset Purchase [Member], USD $)	0 Months Ended
In Thousands, except Share data, unless otherwise specified	Aug. 01, 2013
Colocation Asset Purchase [Member]	'
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]	'
Number of shares issued for acquisition	301,949
Fair value of shares issued for acquisition	$1,637

StockBased_Compensation_StockB

Stock-Based Compensation (Stock-Based Compensation Expense) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]	'	'
Stock-based compensation	$123,100	$42,900
Operating Cost [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]	'	'
Stock-based compensation	-14,400	-3,700
Selling, General and Administrative Expenses [Member]	'	'
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]	'	'
Stock-based compensation	($108,700)	($39,200)

StockBased_Compensation_Narrat

Stock-Based Compensation (Narrative) (Details) (USD $)

3 Months Ended

3 Months Ended

12 Months Ended

3 Months Ended

12 Months Ended

36 Months Ended

12 Months Ended

Sep. 30, 2014

Sep. 30, 2013

Jun. 30, 2014

Sep. 30, 2014

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2013

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2017

Sep. 30, 2014

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

CII [Member]

CII [Member]

CII [Member]

Maximum [Member]

Class A [Member]

Class A [Member]

Common Units [Member]

Common Units [Member]

Preferred Unit Holders [Member]

Preferred Unit Holders [Member]

Preferred Unit Holders [Member]

Common Unit Holders [Member]

CII [Member]

ZPS [Member]

ZPS [Member]

CII [Member]

Minimum [Member]

Maximum [Member]

Minimum [Member]

Stock Comp without Directors

$123,000,000

$42,700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares authorized

'

'

'

625,000,000

'

'

'

'

'

'

'

'

'

'

'

Common units issued

'

'

'

549,268,807

552,512,338

'

'

18,345,417

18,710,000

'

'

'

'

'

'

Common units outstanding

'

'

'

549,268,807,000

552,512,338,000

'

'

18,345,417,000

18,710,000,000

'

'

'

'

'

'

Remaining common units available for issue

'

'

'

75,731,193

72,487,662

'

'

'

'

'

'

'

'

'

'

Stock-based compensation liability

514,200,000

'

392,400,000

'

'

'

'

'

'

'

'

'

'

'

'

Fair value of unvested common units

'

'

'

'

'

'

'

'

'

'

136,500,000

'

'

'

'

Common unit vesting period

'

'

'

'

'

'

'

'

'

'3 years

'

'

'

'

'

Stock-based compensation expense

123,100,000

42,900,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Reimbursement Return

'

'

'

'

'

'

'

'

'

'

'

6.00%

'

'

'

Proceeds from a liquidation event

'

'

'

'

'

'

20.00%

'

'

'

'

'

80.00%

85.00%

15.00%

Maximum incremental allocation of proceeds from a liquidation event

'

'

'

'

'

20.00%

'

'

'

'

'

'

'

'

'

Minimum multiple realized

'

'

'

'

'

'

'

'

'

'

'

3.5

'

'

'

Stock-based compensation related increase to member's interest

$100,000

$232,000

'

'

'

'

'

'

'

'

'

'

'

'

'

StockBased_Compensation_Schedu

Stock-Based Compensation (Schedule of Estimated Fair Value of Common Units) (Details) (USD $)	Sep. 30, 2014	Jun. 30, 2014
Class A [Member]	'	'
Estimated Fair Value Of Common Unit Class	$2.97	$2.47
Class B [Member]	'	'
Estimated Fair Value Of Common Unit Class	$2.68	$2.22
Class C [Member]	'	'
Estimated Fair Value Of Common Unit Class	$2.31	$1.92
Class D [Member]	'	'
Estimated Fair Value Of Common Unit Class	$2.25	$1.86
Class E [Member]	'	'
Estimated Fair Value Of Common Unit Class	$1.95	$1.62
Class F [Member]	'	'
Estimated Fair Value Of Common Unit Class	$1.74	$1.44
Class G [Member]	'	'
Estimated Fair Value Of Common Unit Class	$0.99	$0.82
Class H [Member]	'	'
Estimated Fair Value Of Common Unit Class	$0.84	$0.70
Class I [Member]	'	'
Estimated Fair Value Of Common Unit Class	$0.54	$0.45
Class J [Member]	'	'
Estimated Fair Value Of Common Unit Class	$0.39	$0.33
Class K [Member]	'	'
Estimated Fair Value Of Common Unit Class	$0	$0.29
ZPS [Member] | Class A [Member]	'	'
Estimated Fair Value Of Common Unit Class	$0	$0.09

StockBased_Compensation_Schedu1

Stock-Based Compensation (Schedule of Liquidation Thresholds) (Details) (CII [Member], USD $)	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014
Class A [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	$0
Class B [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	15,000
Class C [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	40,000
Class D [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	45,000
Class E [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	75,000
Class F [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	95,000
Class G [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	235,000
Class H [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	290,000
Class I [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	435,000
Class J [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	515,000
Class K [Member]	'
Liquidation distribution to previous unit holders required to share in liquidation distribution	$545,000

Fair_Value_Measurements_Narrat

Fair Value Measurements (Narrative) (Details) (USD $)	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2014	Jun. 30, 2014
In Thousands, unless otherwise specified			Interest Rate Swap [Member]	Interest Rate Swap [Member]	New Notes [Member]	New Notes [Member]	Term Loan [Member]	Term Loan [Member]
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]	'	'	'	'	'	'	'	'
Carrying value of the notes	$3,255,700	$3,260,800	'	'	$1,250,000	$1,250,000	$1,985,958	$1,990,200
Fair value of the notes	'	'	'	'	1,308,502	1,294,750	'	'
Floor rate	'	'	'	'	'	'	1.00%	'
Percentage over variable rate	'	'	'	'	'	'	3.00%	'
Hypothetical interest rate increase	'	'	10000.00%	'	'	'	1.00%	'
Hypothetical annual interest expense	'	'	16,487	'	'	'	24,600	'
Change in fair value of interest rate swap	'	'	($1,997)	$2,264	'	'	'	'

Fair_Value_Measurements_Schedu

Fair Value Measurements (Schedule Of Financial Instruments Measured At Fair Value On A Recurring Basis) (Details) (USD $)	Sep. 30, 2014	Jun. 30, 2014
In Thousands, unless otherwise specified
Level 2	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Interest Rate Derivative Assets, at Fair Value	$0	$2,000
Level 3	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Stock-based compensation liability	$514,200	$392,400

Commitments_And_Contingencies_

Commitments And Contingencies (Narrative) (Details) (USD $)	Sep. 30, 2014
In Thousands, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]	'
Purchase commitments	$151,000

Related_Party_Transactions_Nar

Related Party Transactions (Narrative) (Details) (USD $)	3 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014	Jul. 02, 2012	Sep. 30, 2014	Jun. 30, 2014
				Matthew Erickson [Member]	Onvoy Voice Services Inc [Member]	Onvoy Voice Services Inc [Member]
Related Party Transaction [Line Items]	'	'	'	'	'	'
Due to related-parties	$0	'	$0	'	$0	'
Due from related parties	2,500,000	'	900,000	'	'	600,000
Due from Affiliates	4.5	'	0.7	'	'	'
Purchase price of notes	'	'	'	600,000	'	'
Accounts payable and accrued liabilities	-46,800,000	-32,800,000	'	'	'	'
Related Party Transaction, Amounts of Transaction	$430,000	'	'	'	'	'

Related_Party_Transactions_Sch

Related Party Transactions (Schedule Of Transactions Recognized With Related-Parties) (Details) (Onvoy Voice Services Inc [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Related Party Transaction [Line Items]	'	'
Revenue	$1.70	$1.70
Operating Cost [Member]	'	'
Related Party Transaction [Line Items]	'	'
Operating costs	($0.30)	($0.40)

Segment_Reporting_Segment_Repo

Segment Reporting Segment Reporting (Narrative) (Details)	3 Months Ended
	Sep. 30, 2014
	Segment
Segment Reporting Information [Line Items]	'
Number of operating segments	3
Minimum [Member] | Raw Infrastructure [Member]	'
Segment Reporting Information [Line Items]	'
Term of Contract	'3 years
Minimum [Member] | Lit Bandwidth [Member]	'
Segment Reporting Information [Line Items]	'
Term of Contract	'2 years
Maximum [Member] | Raw Infrastructure [Member]	'
Segment Reporting Information [Line Items]	'
Term of Contract	'20 years
Maximum [Member] | Lit Bandwidth [Member]	'
Segment Reporting Information [Line Items]	'
Term of Contract	'5 years

Segment_Reporting_Summary_Of_S

Segment Reporting (Summary Of Significant Financial Information) (Details) (USD $)	0 Months Ended	3 Months Ended
	Nov. 26, 2013	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014
Segment Reporting Information [Line Items]	'	'	'	'
Revenue	'	$320,600,000	$269,700,000	'
Adjusted EBITDA	'	183,000,000	157,200,000	'
Total assets	'	5,058,500,000	'	5,049,300,000
Capital expenditures, net of stimulus grant reimbursements	'	-115,300,000	-86,700,000	'
Reconciliations from Net Earnings/(Loss) to Adjusted EBITDA [Abstract]	'	'	'	'
Net loss	'	-110,300,000	-27,500,000	'
Interest expense	'	-46,900,000	-51,500,000	'
(Benefit)/provision for income taxes	'	-9,400,000	-9,300,000	'
Depreciation and amortization expense	'	-96,000,000	-81,000,000	'
Transaction costs	'	-3,200,000	-600,000	'
Stock-based compensation	'	-123,100,000	-42,900,000	'
Loss on extinguishment of debt	-1,000,000	'	'	'
Foreign currency loss/(gain) on intercompany loans	'	-14,700,000	600,000	'
Adjusted EBITDA	'	183,000,000	157,200,000	'
Raw Infrastructure [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenue	'	149,700,000	113,600,000	'
Adjusted EBITDA	'	97,300,000	74,400,000	'
Total assets	'	2,869,500,000	'	2,851,800,000
Capital expenditures, net of stimulus grant reimbursements	'	-68,000,000	-45,200,000	'
Reconciliations from Net Earnings/(Loss) to Adjusted EBITDA [Abstract]	'	'	'	'
Adjusted EBITDA	'	97,300,000	74,400,000	'
Lit Bandwidth [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenue	'	156,100,000	149,400,000	'
Adjusted EBITDA	'	82,200,000	80,900,000	'
Total assets	'	1,772,600,000	'	1,739,100,000
Capital expenditures, net of stimulus grant reimbursements	'	-46,100,000	-41,500,000	'
Reconciliations from Net Earnings/(Loss) to Adjusted EBITDA [Abstract]	'	'	'	'
Adjusted EBITDA	'	82,200,000	80,900,000	'
Other Segments [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenue	'	14,800,000	6,700,000	'
Adjusted EBITDA	'	3,500,000	1,900,000	'
Total assets	'	131,800,000	'	43,100,000
Capital expenditures, net of stimulus grant reimbursements	'	-1,200,000	0	'
Reconciliations from Net Earnings/(Loss) to Adjusted EBITDA [Abstract]	'	'	'	'
Adjusted EBITDA	'	3,500,000	1,900,000	'
Corporate [Member]	'	'	'	'
Segment Reporting Information [Line Items]	'	'	'	'
Revenue	'	0	0	'
Adjusted EBITDA	'	0	0	'
Total assets	'	284,600,000	'	415,300,000
Capital expenditures, net of stimulus grant reimbursements	'	0	0	'
Reconciliations from Net Earnings/(Loss) to Adjusted EBITDA [Abstract]	'	'	'	'
Adjusted EBITDA	'	$0	$0	'

Condensed_Consolidating_Financ2

Condensed Consolidating Financial Information (Narrative) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Jul. 02, 2012	Jul. 02, 2012
	Zayo Capital Inc [Member]	Senior Secured Notes [Member]	Senior Unsecured Notes [Member]
Condensed Consolidating Financial Information [Line Items]	'	'	'
Ownership percentage in subsidiary	100.00%	'	'
Notes face amount	'	$750	$500

Condensed_Consolidating_Financ3

Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Balance Sheet) (Details) (USD $)	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2013	Jun. 30, 2012
Other Assets, Noncurrent	$41,100,000	$37,800,000	'	'
Due from Related Parties, Noncurrent	0	'	'	'
Cash and cash equivalents	167,300,000	297,400,000	97,400,000	91,300,000
Trade receivables, net	64,500,000	59,000,000	'	'
Due from related parties	2,500,000	900,000	'	'
Prepaid expenses	28,800,000	25,600,000	'	'
Deferred income taxes	160,300,000	160,400,000	'	'
Other assets, current	2,900,000	2,400,000	'	'
Assets, Current	426,300,000	545,700,000	'	'
Property and equipment, net	2,895,700,000	2,821,400,000	'	'
Intangible assets, net	735,500,000	709,700,000	'	'
Goodwill	874,300,000	845,300,000	'	'
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	'	0	'	'
Debt issuance costs, net	85,600,000	89,400,000	'	'
Deferred income taxes, net	'	37,800,000	'	'
Other assets, non-current	'	0	'	'
Investment in subsidiary	0	0	'	'
Total assets	5,058,500,000	5,049,300,000	'	'
Current portion of long-term debt	20,500,000	20,500,000	'	'
Accounts payable	28,500,000	27,000,000	'	'
Accrued liabilities	160,900,000	159,600,000	'	'
Accrued interest	26,000,000	57,100,000	'	'
Capital lease obligations, current	3,100,000	2,400,000	'	'
Due to related-parties	0	0	'	'
Deferred revenue, current	92,700,000	75,400,000	'	'
Total current liabilities	331,700,000	342,000,000	'	'
Long-term debt, non-current	3,215,500,000	3,219,700,000	'	'
Related party debt, long-term	0	0	'	'
Capital lease obligations, non-current	23,300,000	22,900,000	'	'
Deferred revenue, non-current	512,600,000	496,900,000	'	'
Deferred income taxes, net	162,000,000	151,800,000	'	'
Stock-based compensation liability	514,200,000	392,400,000	'	'
Other long-term liabilities	20,400,000	22,300,000	'	'
Total liabilities	4,779,700,000	4,648,000,000	'	'
Member's interest	729,000,000	728,900,000	'	'
Accumulated other comprehensive income/(loss)	2,100,000	14,400,000	'	'
(Accumulated deficit)/retained earnings	-452,300,000	-342,000,000	'	'
Total member's equity	278,800,000	401,300,000	'	'
Total liabilities and member's equity	5,058,500,000	5,049,300,000	'	'
Zayo Group, LLC [Member]	'	'	'	'
Other Assets, Noncurrent	24,500,000	'	'	'
Due from Related Parties, Noncurrent	301,500,000	'	'	'
Cash and cash equivalents	146,100,000	260,800,000	88,900,000	86,800,000
Trade receivables, net	31,600,000	37,500,000	'	'
Due from related parties	2,400,000	1,100,000	'	'
Prepaid expenses	19,200,000	18,900,000	'	'
Deferred income taxes	158,900,000	158,900,000	'	'
Other assets, current	1,500,000	1,900,000	'	'
Assets, Current	359,700,000	479,100,000	'	'
Property and equipment, net	2,438,200,000	2,402,400,000	'	'
Intangible assets, net	574,900,000	584,400,000	'	'
Goodwill	682,400,000	682,300,000	'	'
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	'	0	'	'
Debt issuance costs, net	85,600,000	89,400,000	'	'
Deferred income taxes, net	'	23,600,000	'	'
Other assets, non-current	'	267,800,000	'	'
Investment in subsidiary	360,300,000	303,700,000	'	'
Total assets	4,827,100,000	4,832,700,000	'	'
Current portion of long-term debt	20,500,000	20,500,000	'	'
Accounts payable	20,700,000	20,700,000	'	'
Accrued liabilities	128,900,000	126,000,000	'	'
Accrued interest	26,000,000	57,100,000	'	'
Capital lease obligations, current	1,600,000	1,500,000	'	'
Due to related-parties	0	0	'	'
Deferred revenue, current	59,800,000	56,900,000	'	'
Total current liabilities	257,500,000	282,700,000	'	'
Long-term debt, non-current	3,215,500,000	3,219,700,000	'	'
Related party debt, long-term	0	0	'	'
Capital lease obligations, non-current	5,600,000	5,600,000	'	'
Deferred revenue, non-current	483,500,000	459,500,000	'	'
Deferred income taxes, net	112,900,000	345,000,000	'	'
Stock-based compensation liability	452,400,000	106,500,000	'	'
Other long-term liabilities	10,100,000	12,400,000	'	'
Total liabilities	4,537,500,000	4,431,400,000	'	'
Member's interest	776,600,000	778,000,000	'	'
Accumulated other comprehensive income/(loss)	0	0	'	'
(Accumulated deficit)/retained earnings	-487,000,000	-376,700,000	'	'
Total member's equity	289,600,000	401,300,000	'	'
Total liabilities and member's equity	4,827,100,000	4,832,700,000	'	'
Zayo Colocation Inc [Member]	'	'	'	'
Other Assets, Noncurrent	4,200,000	'	'	'
Due from Related Parties, Noncurrent	0	'	'	'
Cash and cash equivalents	1,000,000	1,000,000	5,300,000	1,000,000
Trade receivables, net	6,900,000	6,000,000	'	'
Due from related parties	0	0	'	'
Prepaid expenses	3,100,000	1,400,000	'	'
Deferred income taxes	0	0	'	'
Other assets, current	0	0	'	'
Assets, Current	11,000,000	8,400,000	'	'
Property and equipment, net	111,600,000	95,200,000	'	'
Intangible assets, net	58,500,000	29,800,000	'	'
Goodwill	31,700,000	17,800,000	'	'
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	'	0	'	'
Debt issuance costs, net	0	0	'	'
Other assets, non-current	'	3,300,000	'	'
Investment in subsidiary	0	0	'	'
Total assets	217,000,000	154,500,000	'	'
Current portion of long-term debt	0	0	'	'
Accounts payable	2,200,000	4,300,000	'	'
Accrued liabilities	7,800,000	7,000,000	'	'
Accrued interest	0	0	'	'
Capital lease obligations, current	1,500,000	900,000	'	'
Due to related-parties	0	0	'	'
Deferred revenue, current	1,500,000	1,400,000	'	'
Total current liabilities	13,000,000	13,600,000	'	'
Long-term debt, non-current	0	0	'	'
Related party debt, long-term	0	0	'	'
Capital lease obligations, non-current	16,100,000	15,600,000	'	'
Deferred revenue, non-current	4,000,000	4,000,000	'	'
Deferred income taxes, net	0	22,200,000	'	'
Stock-based compensation liability	28,500,000	0	'	'
Other long-term liabilities	10,100,000	9,800,000	'	'
Total liabilities	71,700,000	65,200,000	'	'
Member's interest	104,000,000	49,600,000	'	'
Accumulated other comprehensive income/(loss)	0	0	'	'
(Accumulated deficit)/retained earnings	41,300,000	39,700,000	'	'
Total member's equity	145,300,000	89,300,000	'	'
Total liabilities and member's equity	217,000,000	154,500,000	'	'
Non-Guarantor Subsidiaries [Member]	'	'	'	'
Other Assets, Noncurrent	12,400,000	'	'	'
Due from Related Parties, Noncurrent	0	'	'	'
Cash and cash equivalents	20,200,000	35,600,000	3,200,000	3,500,000
Trade receivables, net	26,000,000	15,500,000	'	'
Due from related parties	1,100,000	600,000	'	'
Prepaid expenses	6,500,000	5,300,000	'	'
Deferred income taxes	1,400,000	1,500,000	'	'
Other assets, current	1,400,000	500,000	'	'
Assets, Current	56,600,000	59,000,000	'	'
Property and equipment, net	345,900,000	323,800,000	'	'
Intangible assets, net	102,100,000	95,500,000	'	'
Goodwill	160,200,000	145,200,000	'	'
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	'	0	'	'
Debt issuance costs, net	0	0	'	'
Deferred income taxes, net	'	10,900,000	'	'
Other assets, non-current	'	0	'	'
Investment in subsidiary	0	0	'	'
Total assets	677,200,000	634,400,000	'	'
Current portion of long-term debt	0	0	'	'
Accounts payable	5,600,000	2,000,000	'	'
Accrued liabilities	24,200,000	26,600,000	'	'
Accrued interest	0	0	'	'
Capital lease obligations, current	0	0	'	'
Due to related-parties	1,000,000	800,000	'	'
Deferred revenue, current	31,400,000	17,100,000	'	'
Total current liabilities	62,200,000	46,500,000	'	'
Long-term debt, non-current	0	0	'	'
Related party debt, long-term	301,500,000	267,800,000	'	'
Capital lease obligations, non-current	1,600,000	1,700,000	'	'
Deferred revenue, non-current	25,100,000	33,400,000	'	'
Deferred income taxes, net	49,100,000	25,200,000	'	'
Stock-based compensation liability	33,300,000	45,300,000	'	'
Other long-term liabilities	200,000	100,000	'	'
Total liabilities	473,000,000	420,000,000	'	'
Member's interest	215,800,000	205,000,000	'	'
Accumulated other comprehensive income/(loss)	2,100,000	14,400,000	'	'
(Accumulated deficit)/retained earnings	-13,700,000	-5,000,000	'	'
Total member's equity	204,200,000	214,400,000	'	'
Total liabilities and member's equity	677,200,000	634,400,000	'	'
Eliminations [Member]	'	'	'	'
Other Assets, Noncurrent	0	'	'	'
Due from Related Parties, Noncurrent	-301,500,000	'	'	'
Cash and cash equivalents	0	0	'	'
Trade receivables, net	0	0	'	'
Due from related parties	-1,000,000	-800,000	'	'
Prepaid expenses	0	0	'	'
Deferred income taxes	0	0	'	'
Other assets, current	0	0	'	'
Assets, Current	-1,000,000	-800,000	'	'
Property and equipment, net	0	0	'	'
Intangible assets, net	0	0	'	'
Goodwill	0	0	'	'
Deferred Income Taxes and Other Tax Liabilities, Noncurrent	'	0	'	'
Debt issuance costs, net	0	0	'	'
Deferred income taxes, net	'	0	'	'
Other assets, non-current	'	-267,800,000	'	'
Investment in subsidiary	-360,300,000	-303,700,000	'	'
Total assets	-662,800,000	-572,300,000	'	'
Current portion of long-term debt	0	0	'	'
Accounts payable	0	0	'	'
Accrued liabilities	0	0	'	'
Accrued interest	0	0	'	'
Capital lease obligations, current	0	0	'	'
Due to related-parties	-1,000,000	-800,000	'	'
Deferred revenue, current	0	0	'	'
Total current liabilities	-1,000,000	-800,000	'	'
Long-term debt, non-current	0	0	'	'
Related party debt, long-term	-301,500,000	-267,800,000	'	'
Capital lease obligations, non-current	0	0	'	'
Deferred revenue, non-current	0	0	'	'
Deferred income taxes, net	0	0	'	'
Stock-based compensation liability	0	0	'	'
Other long-term liabilities	0	0	'	'
Total liabilities	-302,500,000	-268,600,000	'	'
Member's interest	-367,400,000	-303,700,000	'	'
Accumulated other comprehensive income/(loss)	0	0	'	'
(Accumulated deficit)/retained earnings	7,100,000	0	'	'
Total member's equity	-360,300,000	-303,700,000	'	'
Total liabilities and member's equity	-662,800,000	-572,300,000	'	'
Consolidated Entities [Member]	'	'	'	'
Trade receivables, net	'	$59,000,000	'	'

Condensed_Consolidating_Financ4

Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Operations) (Details) (USD $)	0 Months Ended	3 Months Ended					12 Months Ended
	Nov. 26, 2013	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2014
Revenue	'	$320,600,000	'	'	'	$269,700,000	'
Operating costs, excluding depreciation and amortization	'	107,300,000	92,800,000	85,000,000	85,800,000	79,700,000	343,300,000
Selling, general and administrative expenses, excluding stock-based compensation	'	156,600,000	'	'	'	'	'
Selling, general and administrative expenses	'	156,600,000	124,600,000	96,600,000	87,000,000	76,400,000	384,600,000
Depreciation and amortization	'	96,000,000	'	'	'	81,000,000	'
Total operating costs and expenses	'	359,900,000	'	'	'	237,100,000	'
Operating income	'	-39,300,000	'	'	'	32,600,000	'
Interest expense	'	46,900,000	'	'	'	51,500,000	'
Loss on extinguishment of debt	1,000,000	'	'	'	'	'	'
Other (expense)/income, net	'	-14,700,000	'	'	'	700,000	'
Equity in net earnings of subsidiaries	'	0	'	'	'	0	'
Total other expense, net	'	-61,600,000	'	'	'	-50,800,000	'
Loss from continuing operations before provision for income taxes	'	-100,900,000	'	'	'	-18,200,000	'
(Benefit)/provision for income taxes	'	9,400,000	'	'	'	9,300,000	'
Net (loss)/earnings	'	-110,300,000	'	'	'	-27,500,000	'
Zayo Group, LLC [Member]	'	'	'	'	'	'	'
Revenue	'	257,200,000	'	'	'	238,800,000	'
Operating costs, excluding depreciation and amortization	'	88,000,000	'	'	'	70,600,000	'
Selling, general and administrative expenses, excluding stock-based compensation	'	126,900,000	'	'	'	66,500,000	'
Depreciation and amortization	'	'	'	'	'	75,400,000	'
Total operating costs and expenses	'	294,900,000	'	'	'	212,500,000	'
Operating income	'	-37,700,000	'	'	'	26,300,000	'
Interest expense	'	-42,400,000	'	'	'	-49,200,000	'
Other (expense)/income, net	'	-14,100,000	'	'	'	30,000	'
Equity in net earnings of subsidiaries	'	-7,100,000	'	'	'	3,300,000	'
Total other expense, net	'	-63,600,000	'	'	'	-45,900,000	'
Loss from continuing operations before provision for income taxes	'	-101,300,000	'	'	'	-19,600,000	'
(Benefit)/provision for income taxes	'	9,000,000	'	'	'	7,800,000	'
Net (loss)/earnings	'	-110,300,000	'	'	'	-27,400,000	'
Zayo Colocation Inc [Member]	'	'	'	'	'	'	'
Revenue	'	24,800,000	'	'	'	16,100,000	'
Operating costs, excluding depreciation and amortization	'	7,600,000	'	'	'	5,700,000	'
Selling, general and administrative expenses, excluding stock-based compensation	'	10,700,000	'	'	'	5,600,000	'
Depreciation and amortization	'	'	'	'	'	2,300,000	'
Total operating costs and expenses	'	22,800,000	'	'	'	13,600,000	'
Operating income	'	2,000,000	'	'	'	2,500,000	'
Interest expense	'	-100,000	'	'	'	-2,200,000	'
Other (expense)/income, net	'	0	'	'	'	0	'
Equity in net earnings of subsidiaries	'	0	'	'	'	0	'
Total other expense, net	'	-100,000	'	'	'	-2,200,000	'
Loss from continuing operations before provision for income taxes	'	1,900,000	'	'	'	300,000	'
(Benefit)/provision for income taxes	'	0	'	'	'	0	'
Net (loss)/earnings	'	1,900,000	'	'	'	300,000	'
Non-Guarantor Subsidiaries [Member]	'	'	'	'	'	'	'
Revenue	'	38,600,000	'	'	'	14,800,000	'
Operating costs, excluding depreciation and amortization	'	11,700,000	'	'	'	3,400,000	'
Selling, general and administrative expenses, excluding stock-based compensation	'	19,000,000	'	'	'	4,300,000	'
Depreciation and amortization	'	'	'	'	'	3,300,000	'
Total operating costs and expenses	'	42,200,000	'	'	'	11,000,000	'
Operating income	'	-3,600,000	'	'	'	3,800,000	'
Interest expense	'	-4,400,000	'	'	'	-100,000	'
Other (expense)/income, net	'	-600,000	'	'	'	700,000	'
Equity in net earnings of subsidiaries	'	0	'	'	'	0	'
Total other expense, net	'	-5,000,000	'	'	'	600,000	'
Loss from continuing operations before provision for income taxes	'	-8,600,000	'	'	'	4,400,000	'
(Benefit)/provision for income taxes	'	400,000	'	'	'	1,500,000	'
Net (loss)/earnings	'	-9,000,000	'	'	'	2,900,000	'
Eliminations [Member]	'	'	'	'	'	'	'
Revenue	'	0	'	'	'	0	'
Operating costs, excluding depreciation and amortization	'	0	'	'	'	0	'
Selling, general and administrative expenses, excluding stock-based compensation	'	0	'	'	'	0	'
Depreciation and amortization	'	'	'	'	'	0	'
Total operating costs and expenses	'	0	'	'	'	0	'
Operating income	'	0	'	'	'	0	'
Interest expense	'	0	'	'	'	0	'
Other (expense)/income, net	'	0	'	'	'	0	'
Equity in net earnings of subsidiaries	'	7,100,000	'	'	'	-3,300,000	'
Total other expense, net	'	7,100,000	'	'	'	-3,300,000	'
Loss from continuing operations before provision for income taxes	'	7,100,000	'	'	'	-3,300,000	'
(Benefit)/provision for income taxes	'	0	'	'	'	0	'
Net (loss)/earnings	'	$7,100,000	'	'	'	($3,300,000)	'

Condensed_Consolidating_Financ5

Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statements Of Cash Flows) (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Net cash provided by operating activities of continuing operations	$118,200	$97,100
Purchases of property and equipment	-115,300	-86,700
Purchases of property and equipment, net of stimulus grants	'	-86,700
Acquisitions, net of cash acquired	-126,500	-300
Net cash used in investing activities of continuing operations	-241,800	-87,000
Payments of Dividends	0	'
Equity contributions	0	600
Distribution to Parent	'	0
Principal repayments on capital lease obligations	-700	-400
Principal repayments on long-term debt	-5,100	-4,100
Payment on intercompany loan	0	0
Payment of early redemption fees on debt extinguished	'	-200
Deferred financing costs	0	-200
Net cash (used in)/provided by financing activities of continuing operations	-5,800	-4,100
Effect of changes in foreign exchange rates on cash	-700	100
Net increase in cash and cash equivalents	-130,100	6,100
Cash and cash equivalents, beginning of period	297,400	'
Cash and cash equivalents, end of period	167,300	97,400
Zayo Group, LLC [Member]	'	'
Net cash provided by operating activities of continuing operations	102,300	86,600
Purchases of property and equipment	-98,500	'
Purchases of property and equipment, net of stimulus grants	'	-80,500
Acquisitions, net of cash acquired	-100	0
Net cash used in investing activities of continuing operations	-98,600	-80,500
Payments of Dividends	0	'
Equity contributions	-69,600	600
Distribution to Parent	'	0
Principal repayments on capital lease obligations	-300	-300
Principal repayments on long-term debt	-5,100	-4,100
Payment on intercompany loan	-43,400	0
Payment of early redemption fees on debt extinguished	'	-200
Net cash (used in)/provided by financing activities of continuing operations	-118,400	-4,000
Effect of changes in foreign exchange rates on cash	0	0
Net increase in cash and cash equivalents	-114,700	2,100
Cash and cash equivalents, beginning of period	260,800	'
Cash and cash equivalents, end of period	146,100	88,900
Zayo Colocation Inc [Member]	'	'
Net cash provided by operating activities of continuing operations	9,000	7,500
Purchases of property and equipment	-10,700	'
Purchases of property and equipment, net of stimulus grants	'	-2,800
Acquisitions, net of cash acquired	-52,500	-300
Net cash used in investing activities of continuing operations	-63,200	-3,100
Payments of Dividends	0	'
Equity contributions	54,600	0
Distribution to Parent	'	0
Principal repayments on capital lease obligations	-400	-100
Principal repayments on long-term debt	0	0
Payment on intercompany loan	0	0
Payment of early redemption fees on debt extinguished	'	0
Net cash (used in)/provided by financing activities of continuing operations	54,200	-100
Effect of changes in foreign exchange rates on cash	0	0
Net increase in cash and cash equivalents	0	4,300
Cash and cash equivalents, beginning of period	1,000	'
Cash and cash equivalents, end of period	1,000	5,300
Non-Guarantor Subsidiaries [Member]	'	'
Net cash provided by operating activities of continuing operations	6,900	3,000
Purchases of property and equipment	-6,100	'
Purchases of property and equipment, net of stimulus grants	'	-3,400
Acquisitions, net of cash acquired	-73,900	0
Net cash used in investing activities of continuing operations	-80,000	-3,400
Payments of Dividends	0	'
Equity contributions	15,000	0
Distribution to Parent	'	0
Principal repayments on capital lease obligations	0	0
Principal repayments on long-term debt	0	0
Payment on intercompany loan	43,400	0
Payment of early redemption fees on debt extinguished	'	0
Net cash (used in)/provided by financing activities of continuing operations	58,400	0
Effect of changes in foreign exchange rates on cash	-700	100
Net increase in cash and cash equivalents	-15,400	-300
Cash and cash equivalents, beginning of period	35,600	'
Cash and cash equivalents, end of period	$20,200	$3,200

Subsequent_Events_Details

Subsequent Events (Details) (USD $)

Sep. 30, 2014

Jun. 30, 2014

Sep. 17, 2014

Sep. 17, 2014

Sep. 17, 2014

Sep. 30, 2014

Jun. 30, 2014

Oct. 09, 2014

Oct. 09, 2014

Sep. 30, 2014

Oct. 09, 2014

Oct. 09, 2014

Oct. 22, 2014

Oct. 22, 2014

Oct. 22, 2014

Oct. 22, 2014

Chief Executive Officer [Member]

ZGH [Member]

ZGH [Member]

CII [Member]

CII [Member]

CII [Member]

CII [Member]

Common Stock [Member]

Common Stock [Member]

Common Stock [Member]

IPO [Member]

IPO [Member]

IPO [Member]

IPO [Member]

Restricted Stock Units (RSUs) [Member]

Restricted Stock Units (RSUs) [Member]

Subsequent Event [Member]

Subsequent Event [Member]

CII [Member]

CII [Member]

Subsequent Event [Member]

ZGH [Member]

CII [Member]

Common Stock [Member]

Chief Executive Officer [Member]

Chief Executive Officer [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Member]

Subsequent Event [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Increase (Decrease) in Deferred Compensation

'

'

'

'

'

'

'

$38,500,000

'

'

'

'

'

'

'

'

Fair value of unvested common units

'

'

'

'

'

'

'

'

'

136,500,000

'

107,900,000

'

'

'

'

Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted

'

'

'

2,800,000

'

'

'

'

'

'

'

'

'

'

'

'

Remaining common units available for issue

'

'

'

'

144,737

75,731,193

72,487,662

'

'

'

'

'

'

'

'

'

Reduction in Executive Salary

'

'

18,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Executive Salary

'

'

400,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Stock or Units Available for Distributions

'

'

'

'

'

'

'

'

'

'

223,000,000

'

'

'

'

'

Shares Issued, Price Per Share

'

'

'

'

'

'

'

'

$19

'

'

'

'

'

'

'

Distribution of Common Stock, Number of Shares Distributed

'

'

'

'

'

'

'

'

206,167,766

'

'

'

'

'

'

'

Stock-based compensation liability

$514,200,000

$392,400,000

'

'

'

'

'

'

$475,700,000

'

'

'

'

'

'

'

Stock Issued During Period, Shares, New Issues

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

24,079,002

Share Price

'

'

'

'

'

'

'

'

'

'

'

'

$19

'

'

'

Shares Sold in Initial Public Offering

'

'

'

'

'

'

'

'

'

'

'

'

'

16,008,679

8,070,323

'

Initial Public Offering, Available Shares to Underwriters

'

'

'

'

'

'

'

'

'

'

'

'

3,026,371

'

'

'