Zayo 10-Q 11 Feb 15 2015 Q2 Quarterly report Financial data

Document_And_Entity_Informatio

Document And Entity Information	6 Months Ended
	Dec. 31, 2014	Feb. 11, 2015
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Dec-14
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
Entity Registrant Name	Zayo Group Holdings, Inc.
Entity Central Index Key	1608249
Current Fiscal Year End Date	-24
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		239,008,679

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Dec. 31, 2014	Jun. 30, 2014
In Millions, unless otherwise specified
Current assets
Cash and cash equivalents	$163.60	$297.40
Trade receivables, net of allowance of $3.6 and $3.7 as of December 31, 2014 and June 30, 2014, respectively	71.8	59
Due from related parties		0.1
Prepaid expenses	26.2	25.6
Deferred income taxes, net	160.3	160.4
Other assets	6.2	2.4
Total current assets	428.1	544.9
Property and equipment, net	2,930.60	2,821.40
Intangible assets, net	719.4	709.7
Goodwill	868.7	845.3
Debt issuance costs, net	74.7	89.4
Other assets	42.4	39.7
Total assets	5,063.90	5,050.40
Current liabilities
Current portion of long-term debt	20.5	20.5
Accounts payable	31.5	27
Accrued liabilities	162.4	162.5
Accrued interest		57.1
Capital lease obligations, current	3.2	2.4
Deferred revenue, current	74.2	75.4
Total current liabilities	291.8	344.9
Long-term debt, non-current	2,961.90	3,219.70
Capital lease obligation, non-current	26.4	22.9
Deferred revenue, non-current	548.9	496.9
Stock-based compensation liability	2	392.4
Deferred income taxes, net	136.1	134.9
Other long-term liabilities	21.8	22.3
Total liabilities	3,988.90	4,634
Commitments and contingencies (Note 11)
Stockholders' equity
Preferred stock, $0.001 par value--50,000,000 shares authorized; no shares issued and outstanding as of December 31, 2014 and June 30, 2014, respectively
Common Stock, $0.001 par value--850,000,000 shares authorized; Issued and outstanding 239,008,679 shares and 223,000,000 shares as of December 31, 2014 and June 30, 2104, respectively	0.2	0.2
Additional paid-in capital	1,519.70	755.4
Accumulated other comprehensive (loss)/income	-6.6	14.4
Accumulated deficit	-438.3	-331.6
Note receivable from shareholder		-22
Total stockholders' equity	1,075	416.4
Total liabilities and stockholders' equity	$5,063.90	$5,050.40

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Dec. 31, 2014	Jun. 30, 2014
In Millions, except Share data, unless otherwise specified
Statement Of Financial Position [Abstract]
Trade receivables allowance	$3.60	$3.70
Preferred Stock, Par value	$0.00	$0.00
Preferred Stock, Shares Authorized	50,000,000	50,000,000
Preferred Stock, Shares Issued	0	0
Preferred Stock, Shares Outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	850,000,000	850,000,000
Common stock, shares issued	239,008,679	223,000,000
Common stock, shares outstanding	239,008,679	223,000,000

Condensed_Consolidated_Stateme

Condensed Consolidated Statements Of Operations (USD $)	3 Months Ended		6 Months Ended
In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Revenue	$323.90	$277	$644.50	$545.10
Operating costs and expenses
Operating costs (excluding depreciation and amortization)	97.8	86	205.1	166
Selling, general and administrative expenses	32.1	86.7	188.9	162.8
Depreciation and amortization	96.9	81.7	192.9	162.7
Total operating costs and expenses	226.8	254.4	586.9	491.5
Operating income	97.1	22.6	57.6	53.6
Other expenses
Interest expense	-53.4	-50.3	-100.3	-101.8
Loss on extinguishment of debt	-30.9	-1.9	-30.9	-1.9
Foreign currency (loss)/gain on intercompany loans	-13.3	0.2	-27.9	0.8
Other (expense)/income, net	-0.1	0.2	-0.2	0.3
Total other expenses, net	-97.7	-51.8	-159.3	-102.6
Loss from operations before income taxes	-0.6	-29.2	-101.7	-49
(Benefit)/provision for income taxes	-4.4	8.4	5	17.7
Income/(loss) from continuing operations	3.8	-37.6	-106.7	-66.7
Earnings from discontinued operations, net of income taxes		0.8		2.5
Net income/(loss)	$3.80	($36.80)	($106.70)	($64.20)
Weighted-average shares used to compute net income/(loss) per share:
Basic	236	223	230	223
Diluted	237	223	230	223
Income/(loss) from continuing operations per share:
Basic	$0.02	($0.17)	($0.46)	($0.30)
Diluted	$0.02	($0.17)	($0.46)	($0.30)
Earnings from discontinued operations per share
Basic and diluted		$0		$0.01
Net income/(loss) per share
Basic	$0.02	($0.17)	($0.46)	($0.29)
Diluted	$0.02	($0.17)	($0.46)	($0.29)

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements Of Comprehensive Loss (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Comprehensive Income Net Of Tax [Abstract]
Net income/(loss)	$3.80	($36.80)	($106.70)	($64.20)
Foreign currency translation adjustments	-8.7	22.4	-21	13.1
Comprehensive loss	($4.90)	($14.40)	($127.70)	($51.10)

Condensed_Consolidated_Stateme2

Condensed Consolidated Statement of Stockholders' Equity (USD $)	Total	Common Stock [Member]	Additional paid-in Capital [Member]	Accumulated Other Comprehensive Income/(Loss) [Member]	Accumulated Deficit [Member]	Note receivable from shareholder
In Millions, except Share data
Balance at Jun. 30, 2014	$416.40	$0.20	$755.40	$14.40	($331.60)	($22)
Balance (in shares) at Jun. 30, 2014	223,000,000	223,000,000
Proceeds from issuance of common stock, initial public offering	282		282
Common stock shares issued as initial public offering		16,008,679
Reclassification of common unit liability to additional paid-in capital	490.2		490.2
Stock-based compensation	14.1		14.1
Non-cash settlement of note receivable from Communications Infrastructure Investments, LLC (Note 8)			-22			22
Foreign currency translation adjustments	-21			-21
Net income/(loss)	-106.7				-106.7
Balance at Dec. 31, 2014	$1,075	$0.20	$1,519.70	($6.60)	($438.30)
Balance (in shares) at Dec. 31, 2014	239,008,679	239,008,679

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (USD $)	6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities
Net loss	($106.70)	($64.20)
Earnings from discontinued operations, net of income taxes		2.5
Loss from continuing operations	-106.7	-66.7
Adjustments to reconcile net loss to net cash provided by operating activities of continuing operations
Depreciation and amortization	192.9	162.7
Loss on extinguishment of debt	30.9	1.9
Non-cash interest expense	9.4	10.5
Non-cash loss on investments	0.5
Stock-based compensation	117.1	99.9
Amortization of deferred revenue	-34.6	-26.2
Additions to deferred revenue	84.1	47.4
Provision for bad debts	0.9	0.8
Foreign currency loss/(gain) on intercompany loans	27.9	-0.8
Deferred income taxes	-0.7	15.6
Changes in operating assets and liabilities, net of acquisitions
Trade receivables	-5	14.8
Prepaid expenses	0.2	1.7
Accounts payable and accrued liabilities	-67.5	-16.8
Other assets and liabilities	-7.5	-5.4
Net cash provided by operating activities of continuing operations	241.9	239.4
Cash flows from investing activities
Purchases of property and equipment	-244.8	-175
Net cash used in investing activities of continuing operations	-371.3	-258.5
Cash flows from financing activities
Proceeds from debt		150
Proceeds from revolving credit facility		45
Proceeds from initial public offering	304.2
Direct costs associated with initial public offering	-22.2
Distribution to parent		-1.2
Principal payments on long-term debt	-259.7	-8.5
Payment of early redemption fees on debt extinguished	-23.8
Principal repayments on capital lease obligations	-1.3	-5.9
Payments on revolving credit facility		-45
Payment of debt issuance costs		-1.7
Net cash (used in)/provided by financing activities of continuing operations	-2.8	132.7
Cash flows from continuing operations	-132.2	113.6
Cash flows from discontinued operations
Operating activities		6.4
Investing activities		-2.3
Financing activities		-2.5
Cash flows from discontinued operations		1.6
Effect of changes in foreign exchange rates on cash	-1.6	0.2
Net (decrease)/increase in cash and cash equivalents	-133.8	115.4
Continuing operations:
Cash and cash equivalents, beginning of year	297.4	91.3
Cash flows from continuing operations	-132.2	113.6
Cash flows from discontinued operations		1.6
Effect of changes in foreign exchange rates on cash	-1.6	0.2
Cash and cash equivalents, end of period	163.6	206.7
Supplemental disclosure of non-cash investing and financing activities:
Cash paid for interest, net of capitalized interest - continuing operations	144.7	91.8
Cash paid for interest, net of capitalized interest - discontinued operations		0.2
Cash paid for income taxes	10.8	1.1
Non-cash purchases of equipment through capital leasing	5.8	5.1
Increase/(decrease) in accruals for purchases of property and equipment - continuing operations	5.9	-16.9
Neo Telecoms [Member]
Cash flows from investing activities
Acquisition, net of cash acquired	-73.9
Colo Facilities Atlanta [Member]
Cash flows from investing activities
Acquisition, net of cash acquired	-52.5
Fiber Link [Member]
Cash flows from investing activities
Acquisition, net of cash acquired		-43.1
Access Communications, Inc [Member]
Cash flows from investing activities
Acquisition, net of cash acquired	-0.1	-40.1
Corelink Data Centers [Member]
Cash flows from investing activities
Acquisition, net of cash acquired		($0.30)

Business_and_Basis_of_Presenta

Business and Basis of Presentation	6 Months Ended
	Dec. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Business And Business Of Presentation	(1) BUSINESS AND BASIS OF PRESENTATION
	Business
	Zayo Group Holdings, Inc., a Delaware corporation, was formed on November 13, 2007, and is the parent company of a number of subsidiaries engaged in bandwidth infrastructure provision and services. Zayo Group Holdings, Inc. and its subsidiaries are collectively referred to as “Zayo Group Holdings” or the “Company.” The Company’s primary operating subsidiary is Zayo Group, LLC (“ZGL”). Headquartered in Boulder, Colorado, the Company operates bandwidth infrastructure assets, including fiber networks and 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.
	On October 22, 2014, the Company completed an initial public offering (“IPO”) of shares of its common stock, which were listed on the New York Stock Exchange (“NYSE”) under the ticker symbol “ZAYO”. Prior to its IPO, Zayo Group Holdings was wholly owned by Communications Infrastructure Investments, LLC ("CII"). The Company’s fiscal year ends June 30 each year.  The fiscal year ended June 30, 2014 is referred to as “Fiscal 2014” and the fiscal year ending June 30, 2015 as “Fiscal 2015.”
	Stock Split and Amended and Restated Certificate of Incorporation
	On October 9, 2014, the Company’s Board of Directors approved a 223,000-for-one stock split of the Company’s common stock. The stock split became effective upon filing of the amended and restated certificate of incorporation on October 10, 2014. Immediately subsequent to the stock split, 223,000,000 shares of common stock were outstanding. All of the shares outstanding and per share amounts have been retroactively adjusted to reflect the stock split in the accompanying condensed consolidated financial statements.
	On October 10, 2014, the Company filed its amended and restated certificate of incorporation to authorize the issuance of additional shares of common and preferred stock, establish related voting and holding rights for these shares, and address certain other matters related to corporate governance.
	Initial Public Offering
	On October 22, 2014, the Company completed an IPO of 24,079,002 shares of common stock at an offering price of $19 per share. Shares sold in the IPO consisted of 16,008,679 shares sold by the Company and 8,070,323 shares sold by selling stockholders (including CII investors and employees, former employees, and directors and officers of the Company). 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. Proceeds to the Company after deducting the underwriting discount and other offering expenses totaled approximately $282.0, and net proceeds to selling stockholders, including the exercised underwriter option, totaled approximately $150.2. Proceeds to the Company from the IPO are recorded as an increase in common stock and additional paid-in-capital, net of direct offering costs (including previously capitalized amounts), during the second quarter of Fiscal 2015. The Company’s shares were listed on the New York Stock Exchange (NYSE) on October 17, 2014.
	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 final prospectus filed with the SEC on October 17, 2014. 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 and six-month periods ended December 31, 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.
	Earnings or Loss per Share
	Basic earnings or loss per share attributable to the Company’s common shareholders is computed by dividing net earnings or loss attributable to common shareholders by the weighted average number of common shares outstanding for the period.   Diluted earnings or loss per share attributable to common shareholders presents the dilutive effect, if any, on a per share basis of potential common shares (such as restricted stock units) as if they had been vested or converted during the periods presented.  No such items were included in the computation of diluted loss per share for the six months ended December 31, 2014 or for the three- and six months ended December 31, 2013 because the Company incurred a loss from continuing operations in each of these periods and the effect of inclusion would have been anti-dilutive.
	The effect of 146,001 Part A restricted stock units and 2,210,534 maximum shares that may be issued for Part B restricted stock units outstanding have been included in the computation of diluted income per share for the three months ended December 31, 2014.
	Significant Accounting Policies
	There have been no changes to the Company’s significant accounting policies described in its final prospectus filed with the SEC on October 17, 2014.
	Discontinued Operations
	On June 13, 2014, the Company completed a spin-off of Onvoy, LLC and its subsidiaries (“OVS”) to CII. The spin-off is reported as an equity distribution at carryover basis equal to the net assets and liabilities of OVS on the spin-off date, as the transaction was between entities under common control. See Note 3—Spin-off of Business.
	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 and restricted stock unit grant fair values used to compute the stock-based compensation liability and expense. Management evaluates these estimates and judgments on an ongoing basis and makes estimates based on historical experience, current conditions, and various other assumptions that are believed to be reasonable under the circumstances. The results of these estimates form the basis for making judgments about the carrying values of assets and liabilities as well as identifying and assessing the accounting treatment with respect to commitments and contingencies. Actual results may differ from these estimates under different assumptions or conditions.
	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	6 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Acquisitions	(2) ACQUISITIONS
	As of December 31, 2014 and since its formation, the Company has consummated 32 transactions accounted for as business combinations. The acquisitions were executed as part of the Company’s business strategy of expanding through acquisitions. The acquisitions of these businesses have allowed the Company to increase the scale at which it operates, which in turn affords the Company the ability to increase its operating leverage, extend its network reach, and broaden its customer base.
	The accompanying condensed consolidated financial statements include the operations of the acquired entities from their respective acquisition dates.
	Acquisitions Completed During Fiscal 2015
	Neo Telecoms (“Neo”)
	On July 1, 2014, the Company acquired a 96% equity interest in Neo, a Paris-based bandwidth infrastructure company. The purchase agreement also includes a call option to acquire the remaining equity interest on or after December 31, 2015. The purchase consideration of €54.1 (or $73.9), net of cash acquired, was in consideration of acquiring 96% equity ownership in Neo and a call option to purchase the remaining 4% equity interest in Neo, and is subject to certain adjustments post-closing. The consideration consisted of cash and was paid with cash on hand from the proceeds of the Sixth Amendment to the Company’s term loan facility. €8.7 (or $11.9) of the purchase consideration is currently held in escrow pending the expiration of the indemnification adjustment period. The acquisition was considered an asset purchase for tax purposes.
	Colo Facilities Atlanta (“AtlantaNAP”)
	On July 1, 2014, the Company acquired 100% of the equity interest in AtlantaNAP, a datacenter and managed services provider in Atlanta, for cash consideration of $52.5. $5.3 of the purchase price is currently held in escrow pending the expiration of the indemnification adjustment period. The acquisition was considered an asset purchase for tax purposes.
	Acquisitions Completed During Fiscal 2014
	Corelink Data Centers, LLC (“Corelink”)
	On August 1, 2013, the Company entered into an asset purchase agreement to acquire Corelink. The transaction was consummated on the same date, at which time the Company acquired substantially all of the net assets of this business for consideration of approximately $1.9, comprised of 301,949 preferred units of CII with an estimated fair value of $1.6 and cash of $0.3 net of cash acquired. The acquisition was considered a stock purchase for tax purposes. The 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 price was paid with cash on hand.
	FiberLink, LLC (“FiberLink”)
	On October 2, 2013, the Company acquired 100% of the equity interest in FiberLink, an Illinois limited liability company, for cash consideration of $43.1, which was primarily funded with available funds drawn on the Company’s revolving credit facility. The acquisition was considered an asset purchase for tax purposes.
	CoreXchange, Inc. (“CoreXchange”)
	On March 4, 2014, the Company acquired 100% of the equity interest in CoreXchange, a data center, bandwidth and managed services provider located in Dallas, Texas for consideration of $17.5, 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 revolving credit facility. In conjunction with the acquisition, the Company repaid Geo’s existing debt obligations to the note holders totaling £113.4 and £69.1 was paid to the shareholders. The acquisition was considered an asset purchase for tax purposes.
	Acquisition Method Accounting Estimates
	The Company initially recognizes the assets and liabilities acquired from the aforementioned acquisitions based on its preliminary estimates of their acquisition date fair values. As additional information becomes known concerning the acquired assets and assumed liabilities, management may make adjustments to the opening balance sheet of the acquired company up to the end of the measurement period, which is no longer than a one year period following the acquisition date. The determination of the fair values of the acquired assets and liabilities assumed (and the related determination of estimated lives of depreciable tangible and identifiable intangible assets) requires significant judgment. As of December 31, 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 are preliminary and subject to revision pending the final fair value analysis. During the first quarter of Fiscal 2015, the Company finalized its fair value analysis and resulting purchase accounting for the Access and FiberLink acquisitions consummated in Fiscal 2014.
	The table below reflects the Company's preliminary estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2015 acquisitions:
			AtlantaNAP			Neo
	Acquisition date		1-Jul-14			1-Jul-14
	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			13.7			25.2
	Other assets			—			2.4
	Total assets acquired			54.2			101.2
	Current liabilities			1.4			10.6
	Deferred revenue			0.3			6.3
	Capital lease obligations			—			—
	Deferred tax liability, net			—			6.2
	Total liabilities assumed			1.7			23.1
	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:
		Access			FiberLink				CoreXchange			Geo
	Acquisition date	1-Oct-13			2-Oct-13				4-Mar-14			16-May-14
	Cash	$	1.2		$	—			$	—		$	13.7
	Other current assets		2.3			0.8				0.6			10.7
	Property and equipment		11.5			15.9				3.2			219.5
	Deferred tax assets, net		—			7.7				0.2			—
	Intangibles		18			19.3				11			61.2
	Goodwill		24			19.8				3.6			92.3
	Other assets		—			0.1				—			9.8
	Total assets acquired		57			63.6				18.6			407.2
	Current liabilities		1			1.3				0.5			18.9
	Deferred revenue		5.1			19.2				0.4			44.3
	Capital lease obligations		—			—				0.2			—
	Deferred tax liability, net		9.6			—				—			38
	Total liabilities assumed		15.7			20.5				1.1			101.2
	Net assets acquired		41.3			43.1				17.5			306
	Less cash acquired		(1.2	)		—				—			(13.7	)
	Net consideration paid	$	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 - Access, $18.0; FiberLink, $19.3; CoreXchange, $11.0; 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 Geo, 12 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 carry forwards	$	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 first quarter of Fiscal 2015, the Company finalized its acquisition accounting for Access and FiberLink and its previously reported allocation of the purchase consideration associated with these acquisitions as a result of changes to the original fair value estimates of certain items acquired. These changes are the result of additional information obtained since June 30, 2014 that related to facts and circumstances that existed at the respective acquisition dates. Related to the Access acquisition, property, plant and equipment increased by $3.1, customer relationship intangible assets increased by $2.0, and deferred tax liabilities increased by $2.0 related to the Company's final valuation of non-working capital acquired assets and the related deferred tax impacts. Related to the FiberLink acquisition, property, plant and equipment increased by $9.9, customer relationship intangible assets increased by $2.1, and deferred tax assets increased by $0.7 related to the Company's final valuation of non-working capital acquired assets and the related deferred tax impacts. The Company has recast the previously reported consolidated balance sheet as of June 30, 2014 in connection with the finalization of acquisition accounting for these acquisitions. The Company did not recast the previously reported consolidated statement of operations for the year ended June 30, 2014 due to the immaterial effect of the related adjustments.
Fibergate Holdings, Inc. (“Fibergate”) Settlement
On August 31, 2012, the Company acquired 100% of the equity interest in Fibergate, a privately held corporation, for total consideration of $118.3.  $17.6 of the purchase price was held in escrow pending the expiration of the working capital and indemnification adjustment period. Prior to the expiration of the indemnification adjustment period, the Company filed an indemnification claim against the former owners of Fibergate.  During the three months ended December 31, 2014, the Company and the former owners of Fibergate entered into a settlement agreement and mutual release, which resulted in a refund of $2.5 of the purchase price.  The $2.5 proceeds are included as a reduction to selling, general and administrative expenses on the condensed consolidated statement of operations for the three and six months ended December 31, 2014.
Transaction Costs
Transaction costs include expenses associated with professional services (i.e., legal, accounting, regulatory, etc.) rendered in connection with signed and/or closed acquisitions or disposals (including spin-offs), travel expense, severance expense incurred on the date of acquisition or disposal, and other direct expenses incurred that are associated with such acquisitions or disposals. The Company incurred transaction costs of $1.3 and $4.8 during the three and six months ended December 31, 2014, respectively, and $0.2 and $0.8 during the three and six months ended December 31, 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 net income/ (loss) for the periods ended December 31, 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 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 December 31,							Six months ended December 31,
	2014			2013				2014			2013
Revenue	$	323.9		$	303.3			$	644.5		$	602.3
Net income/(loss)		3.8			(39.2	)			(106.7	)		(68.4	)
The Company is unable to determine the amount of revenue and net income associated with each acquisition recognized in the post-acquisition period as a result of integration activities.

SpinOff_Of_Business

Spin-Off Of Business	6 Months Ended
	Dec. 31, 2014
Discontinued Operations And Disposal Groups [Abstract]
Spin-Off Of Business	(3) SPIN-OFF OF BUSINESS
	On June 13, 2014, the Company completed a spin-off of OVS, a company that provides voice and managed services. Prior to the spin-off, on March 7, 2014, OVS converted from a corporation to a limited liability company. At that time, certain tax attributes were retained by the Company in connection with the conversion, primarily deferred tax assets associated with net operating loss carry forwards totaling $13.7. On the spin-off date, the remaining net assets of OVS were distributed to CII.
	The spin-off is reported as an equity distribution at carryover basis equal to the net assets and liabilities of OVS on the spin-off date, as the transaction was between entities under common control.
	The Company determined that all significant cash flows and continuing involvement associated with the operations of OVS were discontinued. The results of operations of OVS are reported as discontinued operations in the accompanying consolidated financial statements for all periods presented and are presented net of intercompany eliminations.
	Earnings from discontinued operations, net of income taxes in the accompanying consolidated statements of operations are comprised of the following:
		Three months ended December 31,			Six months ended December 31,
		2013			2013
	Revenue	$	19.9		$	40
	Earnings before income taxes	$	2.8		$	5.9
	Income tax expense		(2.0	)		(3.4	)
	Earnings from discontinued	$	0.8		$	2.5
	operations, net of income taxes

Goodwill

Goodwill	6 Months Ended
	Dec. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill	(4) GOODWILL
	The Company’s goodwill balance was $868.7 and $845.3 as of December 31, 2014 and June 30, 2014, respectively. Additions to goodwill during the six months ended December 31, 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 Zayo Professional Services ("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		—			—			—		—			—			—		13.7			—			13.7
	Neo		—			—			—		—			—			—		—			25.2			25.2
	Foreign currency translation		(5.7	)		(5.8	)		—		(0.1	)		(0.2	)		—		(0.9	)		(2.8	)		(15.5	)
	As of December 31, 2014	$	264.2		$	264.2		$	50.3	$	96.6		$	80.2		$	43.7	$	32.4		$	37.1		$	868.7
	During the six months ended December 31, 2014, goodwill decreased by $15.5 due to foreign currency movements impacting goodwill allocated to the U.K. and France operations.
	In addition, the Company has recast goodwill reported in the consolidated balance sheet as of June 30, 2014 in connection with the Company’s final valuation of property, plant and equipment and intangible assets and associated deferred taxes impact for the Access and FiberLink acquisitions, which resulted in a net decrease to goodwill of $15.8 (see Note 2 - Acquisitions).
	Previously reported provisional allocations of goodwill to the Waves and Dark Fiber reporting units have been adjusted as of June 30, 2014 in relation to the Geo acquisition, with a corresponding increase in goodwill allocated to the Waves SPG of $27.5 and an offsetting decrease in goodwill allocated to the Dark Fiber reporting unit.

Intangible_Assets

Intangible Assets	6 Months Ended
	Dec. 31, 2014
Intangible Assets Net Excluding Goodwill [Abstract]
Intangible Assets	(5) INTANGIBLE ASSETS
	Identifiable acquisition-related intangible assets as of December 31, 2014 and June 30, 2014 were as follows:
		Gross		Accumulated			Net
		Carrying		Amortization
		Amount
	31-Dec-14
	Finite-Lived Intangible Assets
	Customer relationships	$	822	$	(125.5	)	$	696.5
	Trade names		0.1		—			0.1
	Underlying rights		1.7		(0.1	)		1.6
	Total		823.8		(125.6	)		698.2
	Indefinite-Lived Intangible Assets
	Certifications		3.5		—			3.5
	Underlying Rights		17.7		—			17.7
	Total	$	845	$	(125.6	)	$	719.4
	30-Jun-14
	Finite-Lived Intangible Assets
	Customer relationships	$	789.2	$	(104.2	)	$	685
	Trade names		0.1		—			0.1
	Underlying rights		1.8		(0.1	)		1.7
	Total		791.1		(104.3	)		686.8
	Indefinite-Lived Intangible Assets
	Certifications		3.5		—			3.5
	Underlying rights		19.4		—			19.4
	Total	$	814	$	(104.3	)	$	709.7

LongTerm_Debt

Long-Term Debt	6 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Long-Term Debt	(6) LONG-TERM DEBT
	As of December 31, 2014 and June 30, 2014, long-term debt was as follows:
	(dollars in millions)	December 31,			June 30,
		2014			2014
	Term Loan Facility due 2019	$	2,000.50		$	2,010.80
	8.125% Senior Secured Notes due 2020		675			750
	10.125% Senior Unsecured Notes due 2020		325.6			500
	Total debt obligations		3,001.10			3,260.80
	Unamortized discount on Term Loan Facility due 2019		(18.7	)		(20.6	)
	Carrying value of debt		2,982.40			3,240.20
	Less current portion		(20.5	)		(20.5	)
	Long-term debt, less current portion	$	2,961.90		$	3,219.70
	On July 2, 2012, ZGL and Zayo Capital, Inc. (“Zayo Capital”) issued $750.0 aggregate principal amount of 8.125% senior secured first-priority notes due 2020 (the “Senior Secured Notes”) and $500.0 aggregate principal amount of 10.125% senior unsecured notes due 2020 (the “Senior Unsecured Notes”, and together with the Senior Secured Notes, the “Existing Notes”). On July 2, 2012, ZGL 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 six months ended December 31, 2014 and 2013, respectively).
	On November 26, 2013, ZGL and Zayo Capital entered into a Fifth Amendment (the “Fifth Amendment”) to the Company’s Credit Agreement. Under the terms of the Fifth Amendment, the Term Loan Facility was increased by $150.0 to $1,749.8, and the interest rate was adjusted to LIBOR plus 3.0% with a minimum LIBOR rate of 1.0%. The amended terms represented a downward adjustment of 50 basis points on the interest rate from the Fourth Amendment (the “Fourth Amendment”) to the Credit Agreement. The interest rate on the Revolver was amended to LIBOR plus 2.75% (based on the Company’s current leverage ratio), which represented a downward adjustment of 25 basis points on the interest rate from the Fourth Amendment. In connection with the Fifth Amendment, the Company did not incur a re-pricing premium.
	Also, in connection with the Fifth Amendment, the Company recognized an expense during the second quarter of Fiscal 2014 of $1.9 associated with debt extinguishment costs, including cash expense of $1.0 related to third party costs and non-cash expense of $0.9 associated with the write-off of the Company’s unamortized debt issuance costs and discount on the Term Loan Facility accounted for as an extinguishment. The Company also incurred an additional $1.5 in debt issuance costs in the second quarter of Fiscal 2014.
	On May 16, 2014, ZGL and Zayo Capital entered into the Sixth Amendment to the Credit Agreement, which increased the Term Loan Facility by $275.0 to $2,015.9. The $275.0 add-on was priced at 99.5%, and the Company incurred debt issuance costs of $3.2. No other terms of the Credit Agreement were amended.
	On December 15, 2014 (the “Redemption Date”), the Company redeemed $75.0 of its outstanding 8.125% Senior Secured Notes at a price of 108.125% of the principal amount and $174.4 of its outstanding 10.125% Senior Unsecured Notes at a price of 110.125% (collectively, the “Note Redemption”). As part of the Note Redemption, the Company recorded an early redemption call premium of $23.8. The call premium has been recorded as a loss on extinguishment of debt on the consolidated statements of operations for the three and six months ended December 31, 2014.
	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 December 31, 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 December 31, 2014, no amounts were outstanding under the Revolver. Standby letters of credit were outstanding in the amount of $8.6 as of December 31, 2014, leaving $241.4 available under the Revolver as of December 31, 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 ZGL to maintain a minimum fixed-charge coverage ratio.
	Pursuant to the Credit Agreement, ZGL shall not permit its Fixed Charge Coverage Ratio, which is defined in the Credit Agreement as the ratio of ZGL'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
	ZGL was in compliance with all covenants associated with its debt agreements as of December 31, 2014.
	Debt issuance costs
	In connection with the Existing Notes offering, Revolver and Term Loan Facility and the subsequent amendments thereto, the Company incurred debt issuance costs of $105.5 (net of extinguishments). These costs are being amortized to interest expense over the respective terms of the underlying debt instruments using the effective interest method, unless extinguished earlier, at which time the related unamortized costs are to be immediately expensed.
	In connection with the Note Redemption, net unamortized debt issuance costs of $7.1 were recorded as part of the loss on extinguishment of debt during the three and six months ended December 31, 2014.
	The balance of debt issuance costs as of December 31, 2014 and June 30, 2014 was $74.7 and $89.4, net of accumulated amortization of $30.8 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 $7.5 during the three and six months ended December 31, 2014, respectively and $3.4 and $6.8 during the three and six months ended December 31, 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 and six months ended December 31, 2014, respectively, $1.5 and ($0.5) was recorded as an increase/(decrease) in interest expense for the change in the fair value of the interest rate swaps.  During the three and six months ended December 31, 2013, respectively, $(0.4) and $1.9 was recorded as an increase/(decrease) in interest expense for the change in the fair value of the interest rate swaps. The fair value of the interest rate swaps of $1.5 and $2.0 is included in “Other long term liabilities” in the Company’s consolidated balance sheet as of December 31, 2014 and June 30, 2014, respectively.
	During the three and six months ended December 31, 2014, the Company made payments of $0.8 and $1.6, respectively, on the interest rate swaps.  During the three and six months ended December 31, 2013, the Company made payments of $0.8 and $1.6, respectively, on the interest rate swaps.

Income_Taxes

Income Taxes	6 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Income Taxes	(7) INCOME TAXES
	The Company’s provision/(benefit) for income taxes from continuing operations is summarized as follows:
		Three months ended December 31,						Six months ended December 31,
		2014			2013			2014			2013
	Current income taxes
	Federal	$	1.6		$	—		$	3.1		$	—
	State		0.9			1.3			1.8			2.1
	Foreign		—			—			0.8			-
	Total		2.5			1.3			5.7			2.1
	Deferred income taxes
	Federal		(5.3	)		6.1			1			13
	State		(1.4	)		(0.5	)		(1.2	)		(0.3	)
	Foreign		(0.2	)		1.5			(0.5	)		2.9
	Total		(6.9	)		7.1			(0.7	)		15.6
	Total (benefit)/provision for income taxes	$	(4.4	)	$	8.4		$	5		$	17.7
	The United States and foreign components of income/(loss) from continuing operations before income taxes for the three and six months ended December 31, 2014 and 2013 are as follows:
		Three months ended December 31,						Six months ended December 31,
		2014			2013			2014			2013
	United States	$	0.1		$	(32.1	)	$	(92.5	)	$	(56.4	)
	Foreign		(0.7	)		2.9			(9.2	)		7.4
	Total	$	(0.6	)	$	(29.2	)	$	(101.7	)	$	(49.0	)
	The Company’s effective income tax rate differs from what would be expected if the federal statutory rate were applied to earnings before income taxes primarily because of certain expenses that represent permanent differences between book and tax expenses and deductions, such as stock-based compensation expense associated with the CII common units, that are recorded as an expense for financial reporting purposes but are not deductible for tax purposes.
	Reconciliations of the actual income tax provision and the tax computed by applying the U.S. federal rate to the earnings before income taxes during the three and six-month periods ended December 31, 2014 and 2013 are as follows:
		Three months ended December 31,						Six months ended December 31,
		2014			2013			2014			2013
	Expected benefit at statutory rate	$	(0.3	)	$	(10.1	)	$	(35.6	)	$	(17.0	)
	Increase due to:
	Non-deductible stock-based compensation		(5.1	)		22.5			42.1			39.5
	State income taxes (benefit)/provision, net of		—			(1.6	)		(4.5	)		(2.8	)
	federal benefit
	Transaction costs not deductible for tax purposes		0.1			(0.1	)		0.4			0.1
	Foreign tax rate differential		(0.3	)		(0.4	)		0.8			(1.0	)
	Release of accrual for uncertain tax position		—			(2.6	)		—			(2.6	)
	Other, net		1.2			0.7			1.8			1.5
	(Benefit)/provision for income taxes	$	(4.4	)	$	8.4		$	5		$	17.7
	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	6 Months Ended
	Dec. 31, 2014
Stockholders Equity Note [Abstract]
Equity	(8) EQUITY
	Prior to October 16, 2014, the Company was a wholly owned subsidiary of CII. CII was organized on November 6, 2006, and subsequently capitalized on May 7, 2007, with capital contributions from various institutional and founder investors. Prior to October 16, 2014, the Company was controlled by the CII board of managers, which was in turn controlled by the members of CII in accordance with the rights specified in CII’s operating agreement. At formation, 1,000 shares of common stock, par value $0.001, were issued to CII by the Company. On October 9, 2014, the Company’s Board of Directors authorized a 223,000-for-one split of the Company’s common stock that was effective upon the filing of the Company’s amended and restated certificate of incorporation on October 10, 2014. Subsequent to the stock split and prior to the Company’s IPO, 223,000,000 shares of common stock with a par value of $0.001 were outstanding and are retroactively reflected in the Company’s condensed consolidated financial statements and notes thereto.
	As part of the Company’s IPO in October 2014, the Company sold 16,008,679 shares of its common stock at a price of $19 per share, for $304.2 in gross proceeds.  The Company incurred costs directly associated with the IPO of $22.2.  Proceeds from the IPO (net of issuance costs) of $282.0 are reflected on the Company’s condensed consolidated statement of stockholders’ equity during the six months ended December 31, 2014. Following the IPO, the Company has 239,008,679 shares of its common stock outstanding.
	During the six months ended December 31, 2014, there was a deemed modification to the Company’s stock compensation arrangements with employees and directors.  The modification resulted in a reclassification of the previously recorded stock-based compensation liability to additional paid-in capital (see Note 9 – Stock-Based Compensation).
	On October 16, 2014, the Company entered into an agreement with CII which relieved CII of its obligation to repay the Company an outstanding intercompany note receivable balance of $22.0. The cancelation of the intercompany note receivable with CII is reflected on the condensed consolidated statement of stockholders’ equity during the six months ended December 31, 2014 as an increase to additional paid-in-capital of $22.0 and an offsetting decrease to the note receivable from shareholder.

StockBased_Compensation

Stock-Based Compensation	6 Months Ended
	Dec. 31, 2014
Share Based Compensation [Abstract]
Stock-Based Compensation	(9) STOCK-BASED COMPENSATION
	The following tables summarize the Company’s stock-based compensation expense for liability and equity classified awards included in the condensed consolidated statements of operations.
		Three Months Ended December 31,					Six Months Ended December 31,
		2014			2013		2014		2013
	Included in:
	Operating costs	$	0.9		$	4.3	$	15.4	$	8
	Selling, general and administrative expenses		(6.9	)		52.7		101.7		91.9
		$	(6.0	)	$	57	$	117.1	$	99.9
	CII Common units	$	(13.4	)	$	56.9	$	109.6	$	99.6
	CII Preferred units	0.1			0.1		0.2		0.3
	Part A restricted stock units	2.6				—	2.6			—
	Part B restricted stock units	4.7				—	4.7			—
	Total stock-based compensation expense	$	(6.0	)	$	57	$	117.1	$	99.9
	As of December 31, 2014, there were 146,001 Part A RSUs outstanding and 575,660 Part B target RSUs outstanding
	CII Common Units
	Prior to the Company’s IPO, the Company was given authorization by CII to award 625,000,000 of CII’s common units as profits interests to employees, directors, and affiliates of the Company.  The common units were historically considered to be stock-based compensation with terms that required the awards to be classified as liabilities due to cash settlement features. The vested portion of the awards was reported as a liability and the fair value was re-measured at each reporting date until the date of settlement, with a corresponding charge (or credit) to stock-based compensation expense.  In connection with the Company’s IPO and the related amendment to the CII operating agreement, there was a deemed modification to the stock compensation arrangements with the Company’s employees and directors. As a result, previously issued common units which were historically accounted for as liability awards, became classified as equity awards.  Prior to reclassifying the common unit liability to equity, the Company re-measured the fair value of the CII common units factoring in the change in fair value since September 30, 2014 and the change in fair value caused by the modification.  The fair value of these previously vested common units was estimated to be $490.2 on the modification date and this amount is reflected in the Company’s condensed consolidated statement of stockholders’ equity as an increase to additional-paid-in-capital during the six months ended December 31, 2014.   The unrecognized compensation associated with unvested CII common units was $124.1, which will be recognized ratably over the remaining vesting period of the Company’s outstanding common units through May 15, 2017.
	On October 9, 2014, the Company and CII’s board of managers approved a non-liquidating distribution by CII of shares of the Company's common stock held by CII to holders of CII vested common units. Employees and independent directors of the Company with vested CII common units received shares of the Company’s common stock equal in value to the underlying value of their vested CII common units. The total number of shares of the Company’s common stock that were distributed to CII common unit holders in connection with this non-liquidating distribution was 20,460,047 shares.
	Employees with unvested CII common units will continue to receive monthly distributions from CII of the Company’s common stock as they vest under the original terms of the CII common unit grant agreements.  A total of 6,392,071 shares of the Company’s common stock associated with unvested CII common units that will be distributed. In addition, CII may be required to distribute additional shares of the Company’s common stock to CII common unit holders on a quarterly basis through June 30, 2016 based on the Company’s stock price performance, subject to the existing vesting provisions of the CII common units. The shares to be distributed to the common unit holders are based on a pre-existing distribution mechanism, whose primary input is the Company’s stock price at each subsequent measurement date.  Any remaining shares of common stock owned by CII will be distributed to the existing CII preferred unit holders.  The total number of shares of the Company’s common stock that will be distributed to existing CII preferred or common unit holders is 10,294,867 shares.
	The valuation of the CII common units as of the IPO date was determined based on a Monte Carlo simulation.  The Monte Carlo valuation analysis attempts to approximate the probability of certain outcomes by running multiple trial runs, called simulations, using random variables to generate potential future stock prices. This valuation technique was used to estimate the fair value associated with future distributions of common stock to CII common unit holders. The Monte Carlo simulation first projects the number of shares to be distributed by CII to the common unit holders at each subsequent measurement date based on stock price projections under each simulation. Shares attributable to unvested CII common units are subject to the existing vesting provisions of the CII common unit awards.  The estimated future value of shares scheduled to be distributed by CII based on vesting provisions are calculated under each independent simulation. The present value of the number of shares of common stock to be distributed to common unit holders under each simulation is then computed, and the average of each simulation is the fair value of the Company’s common shares to be distributed by CII to the common unit holders. This value was then adjusted for prior non-liquidating distributions made by the Company to derive a value for CII common units by class and on per unit basis. These values were used to calculate the fair value of outstanding CII common units as of the IPO date. Various inputs and assumptions were utilized in the valuation method, including forfeiture behavior, vesting provisions, holding restrictions, peer companies’ historical volatility, and an appropriate risk-free rate.
	CII Preferred Units
	CII has issued preferred units of CII to certain of the Company’s executives and independent directors as compensation. The terms of these preferred unit awards require the Company to record the award as an equity award. The Company estimates the fair value of these equity awards on the grant date and recognizes the related expense over the vesting period of the awards. As these awards have been issued by CII to employees and directors of the Company as compensation, the related expense has been recorded by the Company in the accompanying consolidated statements of operations. The Company recognized stock-based compensation expense and a related increase to the Company’s additional paid-in capital of $0.1 and $0.2 for the three and six months ended December 31, 2014 and $0.1 and $0.3 for the three and six months ended December 31, 2013, respectively, including compensation recorded for preferred units granted in earlier periods.
	Also in connection with the non-liquidating distribution by CII approved on October 9, 2014, the Company’s CEO and independent directors with vested CII preferred units received shares of the Company’s common stock equal to the underlying value of their vested CII preferred units. 256,265 shares of the Company’s common stock were distributed to the Company’s CEO and independent directors equal in value to their vested CII preferred units.
	Performance Incentive Compensation Plan (“PCIP”)
	During October 2014, the Company adopted the 2014 Performance Compensation Incentive Plan (“PCIP”).  The PCIP includes incentive cash compensation (ICC) and equity (in the form of restricted stock units or “RSUs”).  Grants under the PCIP RSU plans are made quarterly for all participants. The PCIP was effective on October 16, 2014 and will remain in effect for a period of 10 years (or through October 16, 2024) unless it is earlier terminated by the Company’s Board of Directors.
	The PCIP has two components: Part A and Part B.
	Part A
	Under Part A of the PCIP, all full-time employees, including the Company’s executives, are eligible to earn quarterly awards of RSUs. Each participant in Part A of the PCIP will have a RSU annual award target value, which will be allocated to each fiscal quarter. The final Part A value awarded to a participant for any fiscal quarter is determined by the Compensation Committee subsequent to the end of the respective performance period taking into account the Company’s measured value creation for the quarter, as well as such other subjective factors that it deems relevant (including group and individual level performance factors). The number of Part A RSUs granted will be calculated based on the final award value determined by the Compensation Committee divided by the average closing price of the Company’s common stock over the last ten trading days of the respective performance period. Part A RSUs will vest assuming continuous employment fifteen months subsequent to the end of the performance period. Upon vesting, the RSUs convert to an equal number of shares of the Company’s common stock.
	During the quarter ended December 31, 2014, the Company recognized $2.0 of compensation expense associated with the vested portion of the Part A awards. The December 31, 2014 quarterly award is recorded as a liability as of December 31, 2014, as the awards represent an obligation denominated in a fixed dollar amount to be settled in a variable number of shares during the quarter ending March 31, 2015. Upon the issuance of the RSUs, the liability is re-measured and then reclassified to additional paid-in capital, with a corresponding charge (or credit) to stock based compensation expense. The value of the remaining unvested RSU’s will be expensed ratably through the vesting date of March 31, 2016. At December 31, 2014, the remaining unrecognized compensation cost to be expensed over the remaining vesting period is $10.2.
	On September 17, 2014, the Company’s Compensation Committee approved a one-time grant of Part A RSUs in an amount equal to $2.8, or 144,737 RSUs, to Dan Caruso, the Company’s Chief Executive Officer. In connection with the grant, Mr. Caruso’s annual salary was reduced to seventeen thousand five hundred dollars from $0.4. The grant was made on November 5, 2014, and the RSUs vest in full on December 31, 2015. During the quarter ended December 31, 2014, the Company recognized $0.4 of stock-based compensation expense associated with this Part A RSU grant, with a corresponding adjustment to additional paid-in-capital as the award is equity classified. The remaining unrecognized compensation cost associated with this Part A RSU grant is $2.4.
	Part B
	Under Part B of the PCIP, participants, who include members of the Company’s senior management team, are awarded quarterly grants of RSUs. The number of the RSUs earned by the participants is based on the Company’s stock price performance over a four fiscal quarter measurement period and vest, assuming continuous employment at the end of the measurement period. The existence of a vesting provision that is associated with the performance of the Company’s stock price is a market condition, which affects the determination of the grant date fair value.  Upon vesting, RSUs convert to an equal number of shares of the Company’s common stock.
	During the quarter ended December 31, 2014, the Company granted 575,660 Part B RSUs.  Depending on the Company’s stock price performance, employees who received Part B RSUs in the quarter ended December 31, 2014 are eligible to earn up to 2,210,534 shares of the Company’s stock.  The grant date fair value of the awards was $36.3, which is being expensed over the performance period through September 30, 2015. The Company recognized stock-based compensation expense of $4.7 million for Part B RSU grants for the three and six months ended December 31, 2014.
	The grant date fair value was estimated utilizing a Monte Carlo simulation.  This simulation estimates the ten-day average closing stock price ending on the vesting date, the stock price performance over the performance period, and the number of common shares to be issued at the vesting date. Various assumptions are utilized in the valuation method, including the target stock price performance ranges and respective share payout percentages, the Company’s historical stock price performance and volatility, peer companies’ historical volatility and an appropriate risk-free rate. The aggregate future value of the grant under each simulation is calculated using the estimated per share value of the common stock at the end of the vesting period multiplied by the number of common shares projected to be granted at the vesting date. The present value of the aggregate grant is then calculated under each of the simulations, resulting in a distribution of potential present values. The fair value of the grant is then calculated based on the average of the potential present values. The remaining unrecognized compensation cost associated with this Part B RSU grant is $31.9 at December 31, 2014.  Assuming the measurement date was the end of the current reporting period - December 31, 2014, the Company would be obligated to issue 2,210,534 common shares for outstanding Part B RSU grants upon vesting.

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Fair Value Measurements	(10) FAIR VALUE MEASUREMENTS
	The Company’s financial instruments consist of cash and cash equivalents, restricted cash, trade receivables, accounts payable, interest rate swaps, long-term debt and stock-based compensation liability. The carrying values of cash and cash equivalents, restricted cash, trade receivables, and accounts payable approximated their fair values at December 31, 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 $1,000.6 and $1,250.0 as of December 31, 2014 and June 30, 2014, respectively. Based on market interest rates for debt of similar terms and average maturities, the fair value of the Company’s notes as of December 31, 2014 and June 30, 2014 was estimated to be $1,083.1 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 $1,981.8 and $1,990.2 as of December 31, 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 of one percentage point above the 1.0% LIBOR floor would increase the Company’s annual interest expense by approximately $20.0 before considering the offsetting effects of the Company’s interest rate swaps.
	The Company’s interest rate swaps are valued using discounted cash flow techniques that use observable market inputs, such as LIBOR-based yield curves, forward rates, and credit ratings. Changes in the fair value of the interest rate swaps of $1.5 and ($0.5) were recorded as an increase/(decrease) to interest expense during the three and six months ended December 31, 2014 and $(0.4) and $1.9 for the three and six months ended December 31, 2013, respectively. A hypothetical increase in LIBOR rates of 100 basis points would increase the fair value of the interest rate swaps by approximately $14.0.
	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	December 31,		June 30,
			2014		2014
	Liabilities Recorded at Fair Value in the Financial
	Statements:
	Interest rate swap	Level 2	$	1.5	$	2
	Stock-based compensation liability	Level 3	$	2	$	392.4

Commitments_and_Contingencies

Commitments and Contingencies	6 Months Ended
	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Commitments And Contingencies	(11) COMMITMENTS AND CONTINGENCIES
	Purchase Commitments
	At December 31, 2014, the Company was contractually committed for $128.9 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	6 Months Ended
	Dec. 31, 2014
Related Party Transaction Due From To Related Party [Abstract]
Related Party Transactions	(12) RELATED PARTY TRANSACTIONS
	The Company has ongoing contractual relationships with OVS, whereby the Company provides OVS and its subsidiaries with bandwidth capacity, and OVS provides the Company and its subsidiaries with voice services. The contractual relationships are based on agreements that were entered into at estimated market rates.
	The following table represents the revenue and expense transactions we recorded with OVS for the periods presented:
		Three months ended						Six months ended
		December 31,						December 31,
		2014			2013			2014			2013
	Revenues	$	1.7		$	1.7		$	3.4		$	3.4
	Operating costs	$	(0.4	)	$	(0.4	)	$	(0.7	)	$	(0.8	)
	Prior to the June 13, 2014 spin-off date of OVS, the revenue and operating costs above were eliminated in consolidation.  Subsequent to June 13, 2014, transactions with OVS are included in the Company’s condensed consolidated statements of operations.
	As of December 31, 2014 and June 30, 2014, the Company had a balance due from OVS in the amount of nil and $0.1, respectively.
	During the quarter ended December 31, 2013, the Board of CII authorized a non-liquidating distribution to certain common unit holders of up to $10.0, and the Company advanced $10.0 to CII, evidenced by an intercompany note receivable. During the quarter ended March 31, 2014, the board of managers of CII authorized and paid a non-liquidating distribution to the Company’s CEO of $3.0 and amended the intercompany note receivable with CII for the incremental distribution. During the quarter ended June 30, 2014, the board of managers of CII authorized and redeemed for cash the vested common units held by a member of management for $9.1 in full and final settlement of his outstanding common unit grants and further amended the intercompany note receivable with CII for the incremental distribution. The amount due to the Company from CII of $22.0 was reflected as a reduction of stockholder’s equity as of June 30, 2014.  As discussed in Note 8 – Equity, the Company and CII entered into an agreement which relieved CII of its obligation to repay the outstanding intercompany note receivable balance. As of December 31, 2014, the Company does not have an outstanding receivable balance from CII.
	Dan Caruso, the Company’s Chief Executive Officer and Chairman of the Board of Directors, is a party to an aircraft charter (or membership) agreement through his affiliate, Bear Equity LLC, for business and personal travel. Under the terms of the charter agreement, all fees for the use of the aircraft are effectively variable in nature. For his business travel on behalf of the Company, Mr. Caruso is reimbursed for his use of the aircraft subject to quarterly and annual maximum reimbursement thresholds approved by the Company’s Nominating and Governance Committee. During the three and six months ended December 31, 2014, the Company reimbursed Mr. Caruso $0.2 and $0.6, respectively, for his business use of the aircraft.

Segment_Reporting

Segment Reporting	6 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Segment Reporting	(13) 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 Zayo Colocation (“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 generally 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 primarily comprised of ZPS and Zayo France. ZPS provides network and technical resources to customers in designing, acquiring and maintaining their networks. Services are typically provided for a term of one year for a fixed recurring monthly fee in the case of network and on an hourly basis for technical resources (usage revenue). Zayo France provides services using the Company's Paris and regional fiber network and nine colocation centers across France.
	Revenues for all of the Company’s products are included in one of the Company’s three reportable segments. The results of operations for each reportable segment include an allocation of certain indirect costs and corporate related costs, including overhead and third party-financed debt. The allocation is based on a percentage that represents management’s estimate of the relative burden each segment bears of indirect and corporate costs. Management has evaluated the allocation methods utilized to allocate these costs and determined they are systematic and rational. Identifiable assets for each reportable segment are reconciled to total consolidated assets including unallocated corporate assets and intersegment eliminations. Unallocated corporate assets consist primarily of cash and deferred taxes. The following tables summarize financial information of each of the segments:
	Segment Adjusted EBITDA
	Segment Adjusted EBITDA is the primary measure used by the Company’s CODM to evaluate segment operating performance.
	The Company defines Segment Adjusted EBITDA as earnings from continuing operations before interest, income taxes, depreciation and amortization (“EBITDA”) adjusted to exclude acquisition or disposal-related transaction costs, losses on extinguishment of debt, stock-based compensation, unrealized foreign currency gains (losses) on an intercompany loan, and non-cash income (loss) on equity and cost method investments. The Company uses Segment Adjusted EBITDA to evaluate operating performance, and this financial measure is among the primary measures used by management for planning and forecasting of future periods. The Company believes that the presentation of Segment Adjusted EBITDA is relevant and useful for investors because it allows investors to view results in a manner similar to the method used by management and facilitates comparison of the Company’s results with the results of other companies that have different financing and capital structures.
	Segment Adjusted EBITDA results, along with other quantitative and qualitative information, are also utilized by the Company and its Compensation Committee for purposes of determining bonus payouts to employees.
	Segment Adjusted EBITDA has limitations as an analytical tool and should not be considered in isolation from, or as a substitute for, analysis of the Company’s results from operations and operating cash flows as reported under GAAP. For example, Segment Adjusted EBITDA:
	·	does not reflect capital expenditures, or future requirements for capital and major maintenance expenditures or contractual commitments;
	·	does not reflect changes in, or cash requirements for, working capital needs;
	·	does not reflect the significant interest expense, or the cash requirements necessary to service the interest payments, on the Company’s debt; and
	·	does not reflect cash required to pay income taxes.
	The Company’s computation of Segment Adjusted EBITDA may not be comparable to other similarly titled measures computed by other companies because all companies do not calculate segment Adjusted EBITDA in the same fashion.
			As of and for the three months ended December 31, 2014
			Physical			Lit Services			Other		Corp/			Total
			Infrastructure								elimination
	Revenue from external customers		$	152.7		$	157.4		$	13.8	$	—		$	323.9
	Segment Adjusted EBITDA		$	102.1		$	84.2		$	3.4	$	—		$	189.7
	Total assets		$	2,878.50		$	1,781.80		$	123.1	$	280.5		$	5,063.90
	Capital expenditures		$	76.6		$	52.5		$	0.4	$	—		$	129.5
			As of and for the six months ended December 31, 2014
			Physical			Lit Services			Other		Corp/			Total
			Infrastructure								elimination
	Revenue from external customers		$	302.4		$	313.5		$	28.6	$	—		$	644.5
	Segment Adjusted EBITDA		$	199.4		$	166.4		$	6.9	$	—		$	372.7
	Capital expenditures		$	144.6		$	98.5		$	1.7	$	—		$	244.8
			As of and for the three months ended December 31, 2013
			Physical			Lit Services			Other		Corp/			Total
			Infrastructure								elimination
	Revenue from external customers		$	120.9		$	151.3		$	6.5	$	(1.7	)	$	277
	Segment Adjusted EBITDA		$	80.2		$	81.1		$	1.8	$	(1.4	)	$	161.7
	Capital expenditures		$	46.7		$	41.6		$	—	$	—		$	88.3
			As of and for the six months ended December 31, 2013
			Physical			Lit Services			Other		Corp/			Total
			Infrastructure								elimination
	Revenue from external customers		$	234.5		$	300.7		$	13.3	$	(3.4	)	$	545.1
	Segment Adjusted EBITDA		$	154.5		$	161.9		$	3.6	$	(2.7	)	$	317.3
	Capital expenditures		$	91.9		$	83.1		$	—	$	—		$	175
			As of June 30, 2014
			Physical			Lit Services			Other		Corp/			Total
			Infrastructure								elimination
	Total assets		$	2,851.80		$	1,739.10		$	43.1	$	416.4		$	5,050.40
	Reconciliation from Segment Adjusted EBITDA to net earnings/(loss) from continuing operations
			Three months ended December 31,
			2014			2013
	Segment Adjusted EBITDA		$	189.7		$	161.7
	Interest expense			(53.4	)		(50.3	)
	Benefit/(provision) for income taxes			4.4			(8.4	)
	Depreciation and amortization expense			(96.9	)		(81.7	)
	Transaction costs			(1.3	)		(0.2	)
	Stock-based compensation			6			(57.0	)
	Loss on extinguishment of debt			(30.9	)		(1.9	)
	Foreign currency loss on intercompany loans			(13.3	)		0.2
	Non-cash loss on investments			(0.5	)		—
Net earnings/(loss) from continuing operations		$	3.8		$	(37.6	)
		Six months ended December 31,
		2014			2013
Segment Adjusted EBITDA		$	372.7		$	317.3
Interest expense			(100.3	)		(101.8	)
Provision for income taxes			(5.0	)		(17.7	)
Depreciation and amortization expense			(192.9	)		(162.7	)
Transaction costs			(4.8	)		(0.8	)
Stock-based compensation			(117.1	)		(99.9	)
Loss on extinguishment of debt			(30.9	)		(1.9	)
Foreign currency loss on intercompany loans			(27.9	)		0.8
Non-cash loss on investments			(0.5	)		—
Net loss from continuing operations		$	(106.7	)	$	(66.7	)

Subsequent_Events

Subsequent Events	6 Months Ended
	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Events	(14) SUBSEQUENT EVENTS
	Recently Closed and Pending Acquisitions
	Acquisition of IdeaTek
	On December 3, 2014, the Company entered into a stock purchase agreement with the shareholders of IdeaTek Systems, Inc. ("IdeaTek").  The acquisition of IdeaTek closed on January 1, 2015. Upon the close of the IdeaTek acquisition, the Company acquired all of the equity interest in IdeaTek. The purchase price, subject to certain post-closing adjustments, was $52.0 and was paid with cash on hand.
	The IdeaTek acquisition added 1,800 route miles to the Company’s network in Kansas, and includes a dense metro footprint in Wichita, Kansas. The network spans across Kansas and connects to approximately 600 cellular towers and over 100 additional buildings.
	Pending Acquisition of Latisys
	On January 13, 2015, the Company entered into an acquisition agreement to acquire the operating units of Latisys Holdings, LLC (“Latisys”), a colocation and infrastructure as a service (“Iaas”) provider for a price of $675.0. The Latisys acquisition will be funded with the proceeds of our Notes Offering (as defined below) and is expected to close in the quarter ending March 31, 2015, subject to customary closing conditions.
	The Latisys acquisition will add colocation and IaaS services through eight datacenters across five markets in Northern Virginia, Chicago, Denver, Orange County and London. The acquired datacenters currently total over 185,000 square feet of billable space and 33 megawatts of critical power.
	Senior Unsecured Notes Offering
	On January 23, 2015,  ZGL and Zayo Capital (the “Issuers”) completed a private offering (the “Notes Offering”) exempt from registration under the Securities Act of 1933, as amended, of $700.0 aggregate principal amount of 6.00% senior unsecured notes due 2023 (the “Notes”). The net proceeds from the Notes Offering will be used to fund the purchase price to be paid in connection with the Company’s pending acquisition of the operating units of Latisys.  Any excess net proceeds will be used for general corporate purposes, which may include repayment of indebtedness, acquisitions, working capital and/or capital expenditures.
	The Notes were issued under an indenture (the “Indenture”) among the Issuers, the guarantors party thereto, and The Bank of New York Mellon Trust Company N.A., as trustee.  Interest on the Notes is payable on April 1 and October 1 of each year, beginning on October 1, 2015.  The Notes will mature on April 1, 2023.  At any time on or after April 1, 2018, the Notes may be redeemed, in whole or in part, at the applicable redemption prices set forth in the Indenture, plus accrued interest.  Before April 1, 2018, the Notes may be redeemed, in whole or in part, at a redemption price equal to 100% of their principal amount, plus accrued interest and a “make-whole” premium.  In addition, before April 1, 2018,  up to 40% of the Notes may be redeemed at a redemption price equal to 106.00% of their principal amount, plus accrued interest, using the proceeds of certain equity offerings.  In the event the Latisys Acquisition Agreement is terminated or the Latisys acquisition is not consummated on or prior to May 4, 2015, the Notes will be required to be redeemed pursuant to a special mandatory redemption at a redemption price equal to the offering price of the Notes, plus accrued and unpaid interest to, but not including, the redemption date.
	The Indenture contains covenants that, among other things, restrict the ability of the Issuers and their restricted subsidiaries to incur additional indebtedness and issue preferred stock; pay dividends or make other distributions with respect to any equity interests, make certain investments or other restricted payments, create liens, sell assets, incur restrictions on the ability of the Issuers’ restricted subsidiaries to pay dividends or make other payments to the Issuers, consolidate or merge with or into other companies or transfer all or substantially all of their assets, engage in transactions with affiliates, and enter into sale and leaseback transactions.  The terms of the Indentures include customary events of default.
	The Notes will be fully and unconditionally guaranteed, jointly and severally, on a senior unsecured basis by all of the Issuers’ current and future domestic restricted subsidiaries and any other restricted subsidiaries of the Issuers that guarantee any indebtedness of the Issuers or any guarantor.

Business_and_Basis_of_Presenta1

Business and Basis of Presentation (Policies)	6 Months Ended
	Dec. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Business Description	Business
	Zayo Group Holdings, Inc., a Delaware corporation, was formed on November 13, 2007, and is the parent company of a number of subsidiaries engaged in bandwidth infrastructure provision and services. Zayo Group Holdings, Inc. and its subsidiaries are collectively referred to as “Zayo Group Holdings” or the “Company.” The Company’s primary operating subsidiary is Zayo Group, LLC (“ZGL”). Headquartered in Boulder, Colorado, the Company operates bandwidth infrastructure assets, including fiber networks and 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.
	On October 22, 2014, the Company completed an initial public offering (“IPO”) of shares of its common stock, which were listed on the New York Stock Exchange (“NYSE”) under the ticker symbol “ZAYO”. Prior to its IPO, Zayo Group Holdings was wholly owned by Communications Infrastructure Investments, LLC ("CII"). The Company’s fiscal year ends June 30 each year.  The fiscal year ended June 30, 2014 is referred to as “Fiscal 2014” and the fiscal year ending June 30, 2015 as “Fiscal 2015.”
Stock Split And Amended And Restated Certificate Of Incorporation.	Stock Split and Amended and Restated Certificate of Incorporation
	On October 9, 2014, the Company’s Board of Directors approved a 223,000-for-one stock split of the Company’s common stock. The stock split became effective upon filing of the amended and restated certificate of incorporation on October 10, 2014. Immediately subsequent to the stock split, 223,000,000 shares of common stock were outstanding. All of the shares outstanding and per share amounts have been retroactively adjusted to reflect the stock split in the accompanying condensed consolidated financial statements.
	On October 10, 2014, the Company filed its amended and restated certificate of incorporation to authorize the issuance of additional shares of common and preferred stock, establish related voting and holding rights for these shares, and address certain other matters related to corporate governance.
Initial Public Offering	Initial Public Offering
	On October 22, 2014, the Company completed an IPO of 24,079,002 shares of common stock at an offering price of $19 per share. Shares sold in the IPO consisted of 16,008,679 shares sold by the Company and 8,070,323 shares sold by selling stockholders (including CII investors and employees, former employees, and directors and officers of the Company). 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. Proceeds to the Company after deducting the underwriting discount and other offering expenses totaled approximately $282.0, and net proceeds to selling stockholders, including the exercised underwriter option, totaled approximately $150.2. Proceeds to the Company from the IPO are recorded as an increase in common stock and additional paid-in-capital, net of direct offering costs (including previously capitalized amounts), during the second quarter of Fiscal 2015. The Company’s shares were listed on the New York Stock Exchange (NYSE) on October 17, 2014.
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 final prospectus filed with the SEC on October 17, 2014. 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 and six-month periods ended December 31, 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.
Earnings or Loss Per Share	Earnings or Loss per Share
	Basic earnings or loss per share attributable to the Company’s common shareholders is computed by dividing net earnings or loss attributable to common shareholders by the weighted average number of common shares outstanding for the period.   Diluted earnings or loss per share attributable to common shareholders presents the dilutive effect, if any, on a per share basis of potential common shares (such as restricted stock units) as if they had been vested or converted during the periods presented.  No such items were included in the computation of diluted loss per share for the six months ended December 31, 2014 or for the three- and six months ended December 31, 2013 because the Company incurred a loss from continuing operations in each of these periods and the effect of inclusion would have been anti-dilutive.
	The effect of 146,001 Part A restricted stock units and 2,210,534 maximum shares that may be issued for Part B restricted stock units outstanding have been included in the computation of diluted income per share for the three months ended December 31, 2014.
Significant Accounting Policies	Significant Accounting Policies
	There have been no changes to the Company’s significant accounting policies described in its final prospectus filed with the SEC on October 17, 2014.
Discontinued Operations	Discontinued Operations
	On June 13, 2014, the Company completed a spin-off of Onvoy, LLC and its subsidiaries (“OVS”) to CII. The spin-off is reported as an equity distribution at carryover basis equal to the net assets and liabilities of OVS on the spin-off date, as the transaction was between entities under common control. See Note 3—Spin-off of Business.
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 and restricted stock unit grant fair values used to compute the stock-based compensation liability and expense. Management evaluates these estimates and judgments on an ongoing basis and makes estimates based on historical experience, current conditions, and various other assumptions that are believed to be reasonable under the circumstances. The results of these estimates form the basis for making judgments about the carrying values of assets and liabilities as well as identifying and assessing the accounting treatment with respect to commitments and contingencies. Actual results may differ from these estimates under different assumptions or conditions.
Recently Issued Accounting Pronouncements	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_Tables

Acquisitions (Tables)	6 Months Ended
	Dec. 31, 2014
Business Combinations [Abstract]
Schedule of Acquisitions	The table below reflects the Company's preliminary estimates of the acquisition date fair values of the assets and liabilities assumed from its Fiscal 2015 acquisitions:
			AtlantaNAP			Neo
	Acquisition date		1-Jul-14			1-Jul-14
	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			13.7			25.2
	Other assets			—			2.4
	Total assets acquired			54.2			101.2
	Current liabilities			1.4			10.6
	Deferred revenue			0.3			6.3
	Capital lease obligations			—			—
	Deferred tax liability, net			—			6.2
	Total liabilities assumed			1.7			23.1
	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:
		Access			FiberLink				CoreXchange			Geo
	Acquisition date	1-Oct-13			2-Oct-13				4-Mar-14			16-May-14
	Cash	$	1.2		$	—			$	—		$	13.7
	Other current assets		2.3			0.8				0.6			10.7
	Property and equipment		11.5			15.9				3.2			219.5
	Deferred tax assets, net		—			7.7				0.2			—
	Intangibles		18			19.3				11			61.2
	Goodwill		24			19.8				3.6			92.3
	Other assets		—			0.1				—			9.8
	Total assets acquired		57			63.6				18.6			407.2
	Current liabilities		1			1.3				0.5			18.9
	Deferred revenue		5.1			19.2				0.4			44.3
	Capital lease obligations		—			—				0.2			—
	Deferred tax liability, net		9.6			—				—			38
	Total liabilities assumed		15.7			20.5				1.1			101.2
	Net assets acquired		41.3			43.1				17.5			306
	Less cash acquired		(1.2	)		—				—			(13.7	)
	Net consideration paid	$	40.1		$	43.1			$	17.5		$	292.3
Schedule of Deferred Tax Assets and Liabilities	The tax effect of temporary differences that give rise to significant portions of the net deferred tax liabilities are as follows:
		Geo
		16-May-14
	Deferred income tax assets:
	Net operating loss carry forwards	$	2.5
	Deferred revenue		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	)
Schedule Of Pro-Forma Financial Information (Unaudited)	The unaudited pro forma financial information below is not necessarily indicative of either future results of operations or results that might have been achieved had the acquisitions been consummated as of July 1, 2013.
		Three months ended December 31,							Six months ended December 31,
		2014			2013				2014			2013
	Revenue	$	323.9		$	303.3			$	644.5		$	602.3
	Net income/(loss)		3.8			(39.2	)			(106.7	)		(68.4	)
	The Company is unable to determine the amount of revenue and net income associated with each acquisition recognized in the post-acquisition period as a result of integration activities.

SpinOff_Of_Business_Tables

Spin-Off Of Business (Tables)	6 Months Ended
	Dec. 31, 2014
Discontinued Operations And Disposal Groups [Abstract]
Schedule Of Earnings From Discontinued Operations	Earnings from discontinued operations, net of income taxes in the accompanying consolidated statements of operations are comprised of the following:
		Three months ended December 31,			Six months ended December 31,
		2013			2013
	Revenue	$	19.9		$	40
	Earnings before income taxes	$	2.8		$	5.9
	Income tax expense		(2.0	)		(3.4	)
	Earnings from discontinued	$	0.8		$	2.5
	operations, net of income taxes

Goodwill_Tables

Goodwill (Tables)	6 Months Ended
	Dec. 31, 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		—			—			—		—			—			—		13.7			—			13.7
	Neo		—			—			—		—			—			—		—			25.2			25.2
	Foreign currency translation		(5.7	)		(5.8	)		—		(0.1	)		(0.2	)		—		(0.9	)		(2.8	)		(15.5	)
	As of December 31, 2014	$	264.2		$	264.2		$	50.3	$	96.6		$	80.2		$	43.7	$	32.4		$	37.1		$	868.7

Intangible_Assets_Tables

Intangible Assets (Tables)	6 Months Ended
	Dec. 31, 2014
Intangible Assets Net Excluding Goodwill [Abstract]
Schedule of Intangible Assets	Identifiable acquisition-related intangible assets as of December 31, 2014 and June 30, 2014 were as follows:
		Gross		Accumulated			Net
		Carrying		Amortization
		Amount
	31-Dec-14
	Finite-Lived Intangible Assets
	Customer relationships	$	822	$	(125.5	)	$	696.5
	Trade names		0.1		—			0.1
	Underlying rights		1.7		(0.1	)		1.6
	Total		823.8		(125.6	)		698.2
	Indefinite-Lived Intangible Assets
	Certifications		3.5		—			3.5
	Underlying Rights		17.7		—			17.7
	Total	$	845	$	(125.6	)	$	719.4
	30-Jun-14
	Finite-Lived Intangible Assets
	Customer relationships	$	789.2	$	(104.2	)	$	685
	Trade names		0.1		—			0.1
	Underlying rights		1.8		(0.1	)		1.7
	Total		791.1		(104.3	)		686.8
	Indefinite-Lived Intangible Assets
	Certifications		3.5		—			3.5
	Underlying rights		19.4		—			19.4
	Total	$	814	$	(104.3	)	$	709.7

LongTerm_Debt_Tables

Long-Term Debt (Tables)	6 Months Ended
	Dec. 31, 2014
Debt Disclosure [Abstract]
Schedule of Debt	As of December 31, 2014 and June 30, 2014, long-term debt was as follows:
	(dollars in millions)	December 31,			June 30,
		2014			2014
	Term Loan Facility due 2019	$	2,000.50		$	2,010.80
	8.125% Senior Secured Notes due 2020		675			750
	10.125% Senior Unsecured Notes due 2020		325.6			500
	Total debt obligations		3,001.10			3,260.80
	Unamortized discount on Term Loan Facility due 2019		(18.7	)		(20.6	)
	Carrying value of debt		2,982.40			3,240.20
	Less current portion		(20.5	)		(20.5	)
	Long-term debt, less current portion	$	2,961.90		$	3,219.70
Schedule of Fixed-Charge Coverage Ratios	Pursuant to the Credit Agreement, ZGL shall not permit its Fixed Charge Coverage Ratio, which is defined in the Credit Agreement as the ratio of ZGL'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)	6 Months Ended
	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Schedule of Provision for Income Taxes	The Company’s provision/(benefit) for income taxes from continuing operations is summarized as follows:
Schedule of Income before Income Tax
	The United States and foreign components of income/(loss) from continuing operations before income taxes for the three and six months ended December 31, 2014 and 2013 are as follows:
		Three months ended December 31,						Six months ended December 31,
		2014			2013			2014			2013
	United States	$	0.1		$	(32.1	)	$	(92.5	)	$	(56.4	)
	Foreign		(0.7	)		2.9			(9.2	)		7.4
	Total	$	(0.6	)	$	(29.2	)	$	(101.7	)	$	(49.0	)
Schedule Of Reconciliation Of Income Tax Provision	Reconciliations of the actual income tax provision and the tax computed by applying the U.S. federal rate to the earnings before income taxes during the three and six-month periods ended December 31, 2014 and 2013 are as follows:
		Three months ended December 31,						Six months ended December 31,
		2014			2013			2014			2013
	Expected benefit at statutory rate	$	(0.3	)	$	(10.1	)	$	(35.6	)	$	(17.0	)
	Increase due to:
	Non-deductible stock-based compensation		(5.1	)		22.5			42.1			39.5
	State income taxes (benefit)/provision, net of		—			(1.6	)		(4.5	)		(2.8	)
	federal benefit
	Transaction costs not deductible for tax purposes		0.1			(0.1	)		0.4			0.1
	Foreign tax rate differential		(0.3	)		(0.4	)		0.8			(1.0	)
	Release of accrual for uncertain tax position		—			(2.6	)		—			(2.6	)
	Other, net		1.2			0.7			1.8			1.5
	(Benefit)/provision for income taxes	$	(4.4	)	$	8.4		$	5		$	17.7

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	6 Months Ended
	Dec. 31, 2014
Share Based Compensation [Abstract]
Schedule of Employee Service Share-based Compensation Allocation of Recognized Period Costs	The following tables summarize the Company’s stock-based compensation expense for liability and equity classified awards included in the condensed consolidated statements of operations
		Three Months Ended December 31,					Six Months Ended December 31,
		2014			2013		2014		2013
	Included in:
	Operating costs	$	0.9		$	4.3	$	15.4	$	8
	Selling, general and administrative expenses		(6.9	)		52.7		101.7		91.9
		$	(6.0	)	$	57	$	117.1	$	99.9
	CII Common units	$	(13.4	)	$	56.9	$	109.6	$	99.6
	CII Preferred units	0.1			0.1		0.2		0.3
	Part A restricted stock units	2.6				—	2.6			—
	Part B restricted stock units	4.7				—	4.7			—
	Total stock-based compensation expense	$	(6.0	)	$	57	$	117.1	$	99.9

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Dec. 31, 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	December 31,		June 30,
			2014		2014
	Liabilities Recorded at Fair Value in the Financial
	Statements:
	Interest rate swap	Level 2	$	1.5	$	2
	Stock-based compensation liability	Level 3	$	2	$	392.4

Related_Party_Transactions_Tab

Related Party Transactions (Tables) (O V S)	6 Months Ended
	Dec. 31, 2014
O V S
Related Party Transaction [Line Items]
Revenue and Expense Transactions Recognized	The following table represents the revenue and expense transactions we recorded with OVS for the periods presented:
		Three months ended						Six months ended
		December 31,						December 31,
		2014			2013			2014			2013
	Revenues	$	1.7		$	1.7		$	3.4		$	3.4
	Operating costs	$	(0.4	)	$	(0.4	)	$	(0.7	)	$	(0.8	)

Segment_Reporting_Tables

Segment Reporting (Tables)	6 Months Ended
	Dec. 31, 2014
Segment Reporting [Abstract]
Summary Of Significant Financial Information	The Company’s computation of Segment Adjusted EBITDA may not be comparable to other similarly titled measures computed by other companies because all companies do not calculate segment Adjusted EBITDA in the same fashion.
		As of and for the three months ended December 31, 2014
		Physical			Lit Services			Other		Corp/			Total
		Infrastructure								elimination
	Revenue from external customers	$	152.7		$	157.4		$	13.8	$	—		$	323.9
	Segment Adjusted EBITDA	$	102.1		$	84.2		$	3.4	$	—		$	189.7
	Total assets	$	2,878.50		$	1,781.80		$	123.1	$	280.5		$	5,063.90
	Capital expenditures	$	76.6		$	52.5		$	0.4	$	—		$	129.5
		As of and for the six months ended December 31, 2014
		Physical			Lit Services			Other		Corp/			Total
		Infrastructure								elimination
	Revenue from external customers	$	302.4		$	313.5		$	28.6	$	—		$	644.5
	Segment Adjusted EBITDA	$	199.4		$	166.4		$	6.9	$	—		$	372.7
	Capital expenditures	$	144.6		$	98.5		$	1.7	$	—		$	244.8
		As of and for the three months ended December 31, 2013
		Physical			Lit Services			Other		Corp/			Total
		Infrastructure								elimination
	Revenue from external customers	$	120.9		$	151.3		$	6.5	$	(1.7	)	$	277
	Segment Adjusted EBITDA	$	80.2		$	81.1		$	1.8	$	(1.4	)	$	161.7
	Capital expenditures	$	46.7		$	41.6		$	—	$	—		$	88.3
		As of and for the six months ended December 31, 2013
		Physical			Lit Services			Other		Corp/			Total
		Infrastructure								elimination
	Revenue from external customers	$	234.5		$	300.7		$	13.3	$	(3.4	)	$	545.1
	Segment Adjusted EBITDA	$	154.5		$	161.9		$	3.6	$	(2.7	)	$	317.3
	Capital expenditures	$	91.9		$	83.1		$	—	$	—		$	175
Reconciliation from Total Segment Adjusted EBITDA to Net Earnings/ (Loss) From Continuing Operations before Income Taxes	Reconciliation from Segment Adjusted EBITDA to net earnings/(loss) from continuing operations
		Three months ended December 31,
		2014			2013
	Segment Adjusted EBITDA	$	189.7		$	161.7
	Interest expense		(53.4	)		(50.3	)
	Benefit/(provision) for income taxes		4.4			(8.4	)
	Depreciation and amortization expense		(96.9	)		(81.7	)
	Transaction costs		(1.3	)		(0.2	)
	Stock-based compensation		6			(57.0	)
	Loss on extinguishment of debt		(30.9	)		(1.9	)
	Foreign currency loss on intercompany loans		(13.3	)		0.2
	Non-cash loss on investments		(0.5	)		—
	Net earnings/(loss) from continuing operations	$	3.8		$	(37.6	)
		Six months ended December 31,
		2014			2013
	Segment Adjusted EBITDA	$	372.7		$	317.3
	Interest expense		(100.3	)		(101.8	)
	Provision for income taxes		(5.0	)		(17.7	)
	Depreciation and amortization expense		(192.9	)		(162.7	)
	Transaction costs		(4.8	)		(0.8	)
	Stock-based compensation		(117.1	)		(99.9	)
	Loss on extinguishment of debt		(30.9	)		(1.9	)
	Foreign currency loss on intercompany loans		(27.9	)		0.8
	Non-cash loss on investments		(0.5	)		—
	Net loss from continuing operations	$	(106.7	)	$	(66.7	)

Business_and_Basis_of_Presenta2

Business and Basis of Presentation (Narrative) (Details) (USD $)	0 Months Ended		3 Months Ended	6 Months Ended
In Millions, except Share data, unless otherwise specified	Oct. 22, 2014	Oct. 09, 2014	Dec. 31, 2014	Dec. 31, 2014	Oct. 20, 2014	Oct. 10, 2014	Jun. 30, 2014
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common Stock, Shares, Issued		223,000
Common stock, shares outstanding		223,000,000	239,008,679	239,008,679		223,000,000	223,000,000
Common stock shares issued as initial public offering	16,008,679
Purchase of additional shares from selling stockholder's by underwriters.					3,026,371
Part A Restricted Stock Units
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock units outstanding			146,001
Part B Restricted Stock Units | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock units outstanding			2,210,534
IPO
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Common stock shares issued as initial public offering	24,079,002			16,008,679
Shares of common stock offered in IPO by stockholders	8,070,323
Shares Issued, Price Per Share					19	19
Net proceeds from IPO, after deducting underwriting discounts and other offering expenses.	282			$304.20
Stockholders [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Net proceeds from IPO, after deducting underwriting discounts and other offering expenses.	150.2

Acquisitions_Narrative_Details

Acquisitions (Narrative) (Details)

3 Months Ended

6 Months Ended

92 Months Ended

0 Months Ended

6 Months Ended

0 Months Ended

6 Months Ended

0 Months Ended

6 Months Ended

12 Months Ended

0 Months Ended

6 Months Ended

12 Months Ended

0 Months Ended

12 Months Ended

0 Months Ended

6 Months Ended

12 Months Ended

6 Months Ended

0 Months Ended

3 Months Ended

In Millions, except Share data, unless otherwise specified

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2014

Jul. 03, 2014

Jul. 03, 2014

Dec. 31, 2014

Jul. 01, 2014

Jul. 01, 2014

Jul. 01, 2014

Jul. 03, 2014

Dec. 31, 2014

Jul. 01, 2014

Jun. 30, 2014

Aug. 01, 2013

Oct. 02, 2013

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2014

Oct. 01, 2013

Oct. 02, 2013

Oct. 02, 2013

Dec. 31, 2013

Jun. 30, 2014

Dec. 31, 2014

Mar. 04, 2014

Jun. 30, 2014

Dec. 31, 2014

Mar. 31, 2014

16-May-14

16-May-14

Dec. 31, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Aug. 31, 2012

Dec. 31, 2014

USD ($)

USD ($)

USD ($)

USD ($)

business_combination

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Neo Telecoms [Member]

Atlanta NAP [Member]

Atlanta NAP [Member]

Atlanta NAP [Member]

Atlanta NAP [Member]

Colocation Acquisition [Member]

Access [Member]

Access [Member]

Access [Member]

Access [Member]

Access [Member]

Fiber Link [Member]

Fiber Link [Member]

Fiber Link [Member]

Fiber Link [Member]

Fiber Link [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

CoreXchange [Member]

Geo [Member]

Geo [Member]

Geo [Member]

Geo [Member]

CoreLink [Member]

Fiberlink Llc

Fibergate Holdings Inc [Member]

Fibergate Holdings Inc [Member]

USD ($)

EUR (€)

USD ($)

USD ($)

EUR (€)

Call Option [Member]

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

USD ($)

GBP (£)

USD ($)

USD ($)

USD ($)

Selling, General and Administrative Expenses [Member]

USD ($)

Business Acquisition [Line Items]

Number of business combinations completed

32

Business acquisition, percentage of voting interests acquired

96.00%

96.00%

4.00%

100.00%

100.00%

100.00%

100.00%

100.00%

100.00%

100.00%

100.00%

Consideration of acquiring equity ownership

$73.90

€ 54.10

$52.50

$0.30

$292.30

£ 174.3

$118.30

Escrow deposit

11.9

8.7

Purchase price, held in escrow

5.3

4

1.8

17.6

Net assets acquired

52.5

1.9

41.3

43.1

43.1

17.5

306

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

301,949

Business acquisition, equity interest issued or issuable, value assigned

1.6

Cash paid for acquisitions, net of cash acquired

73.9

52.5

40.1

43.1

43.1

43.1

17.5

292.3

Notes payable

113.4

Notes payable, related parties

69.1

Intangibles assumed

13.4

30.4

30.4

18

18

19.3

19.3

19.3

11

11

61.2

61.2

Estimated useful life of acquired intangible assets

15 years

11 years

20 years

18 years

11 years

12 years

12 years

Deferred revenue acquired

0.3

5.1

19.2

19.2

0.4

44.3

44.3

Business combination, deferred revenue, weighted average remaining contractual term

9 years 8 months 12 days

Deferred Tax Assets, Net

38

Property plant and equipment purchase accounting adjustments

3.1

9.9

Finite lived intangible assets, purchase accounting adjustments

2

2.1

Deferred tax assets purchase accounting adjustments

2

0.7

Refund of purchase price

2.5

Acquisition related costs

$1.30

$0.20

$4.80

$0.80

Acquisitions_Schedule_of_Acqui

Acquisitions (Schedule of Acquisition) (Details) (USD $)	0 Months Ended				6 Months Ended	0 Months Ended
In Millions, unless otherwise specified	Jul. 03, 2014	Oct. 02, 2013	Oct. 01, 2013	Oct. 02, 2013	Dec. 31, 2013	Mar. 04, 2014	16-May-14	Dec. 31, 2014	Jun. 30, 2014
Business Acquisition [Line Items]
Goodwill								$868.70	$845.30
Atlanta NAP [Member]
Business Acquisition [Line Items]
Acquisition date	1-Jul-14
Other current assets									0.3
Property and equipment									9.7
Deferred tax assets, net									0.1
Intangibles assumed								30.4	30.4
Goodwill									13.7
Total assets acquired									54.2
Current liabilities									1.4
Deferred revenue									0.3
Total liabilities assumed									1.7
Net assets acquired									52.5
Net cash paid	52.5
Neo [Member]
Business Acquisition [Line Items]
Acquisition date	1-Jul-14
Cash acquired									4.2
Other current assets									13.1
Property and equipment									42.9
Intangibles assumed									13.4
Goodwill									25.2
Other assets									2.4
Total assets acquired									101.2
Current liabilities									10.6
Deferred revenue									6.3
Deferred tax liability, net									6.2
Total liabilities assumed									23.1
Net assets acquired									78.1
Less cash acquired									-4.2
Net cash paid	73.9
Access [Member]
Business Acquisition [Line Items]
Acquisition date			1-Oct-13
Cash acquired			1.2
Other current assets			2.3
Property and equipment			11.5
Deferred tax assets, net			0
Intangibles assumed			18					18
Goodwill			24
Total assets acquired			57
Current liabilities			1
Deferred revenue			5.1
Deferred tax liability, net			9.6
Total liabilities assumed			15.7
Net assets acquired			41.3
Less cash acquired			-1.2
Net cash paid		40.1
Fiber Link [Member]
Business Acquisition [Line Items]
Acquisition date		2-Oct-13
Other current assets		0.8		0.8
Property and equipment		15.9		15.9
Deferred tax assets, net		7.7		7.7
Intangibles assumed		19.3		19.3				19.3
Goodwill		19.8		19.8
Other assets		0.1		0.1
Total assets acquired		63.6		63.6
Current liabilities		1.3		1.3
Deferred revenue		19.2		19.2
Total liabilities assumed		20.5		20.5
Net assets acquired		43.1		43.1
Net cash paid		43.1		43.1	43.1
CoreXchange [Member]
Business Acquisition [Line Items]
Acquisition date						4-Mar-14
Other current assets						0.6
Property and equipment						3.2
Deferred tax assets, net						0.2
Intangibles assumed						11		11
Goodwill						3.6
Total assets acquired						18.6
Current liabilities						0.5
Deferred revenue						0.4
Capital lease obligations						0.2
Total liabilities assumed						1.1
Net assets acquired						17.5
Net cash paid						17.5
Geo [Member]
Business Acquisition [Line Items]
Acquisition date							16-May-14
Cash acquired							13.7
Other current assets							10.7
Property and equipment							219.5
Intangibles assumed							61.2	61.2
Goodwill							92.3
Other assets							9.8
Total assets acquired							407.2
Current liabilities							18.9
Deferred revenue							44.3	44.3
Deferred tax liability, net							38
Total liabilities assumed							101.2
Net assets acquired							306
Less cash acquired							-13.7
Net cash paid							$292.30

Acquisitions_Schedule_of_Defer

Acquisitions (Schedule of Deferred Tax Assets and Liabilities) (Details) (USD $)	Dec. 31, 2014	Jun. 30, 2014	Jun. 13, 2014	16-May-14
In Millions, unless otherwise specified
Deferred income tax assets:
Net operating loss carry forwards			$13.70
Deferred income tax liabilities:
Net deferred income tax liabilities	-136.1	-134.9
Geo [Member]
Deferred income tax assets:
Net operating loss carry forwards				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)

Acquisitions_Schedule_of_ProFo

Acquisitions (Schedule of Pro-Forma Financial Information) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Business Combinations [Abstract]
Revenue	$323.90	$303.30	$644.50	$602.30
Net income/(loss)	$3.80	($39.20)	($106.70)	($68.40)

SpinOff_Of_Business_Narrative_

Spin-Off Of Business (Narrative) (Details) (USD $)	Jun. 13, 2014
In Millions, unless otherwise specified
Discontinued Operations And Disposal Groups [Abstract]
Net operating loss carry forwards	$13.70

SpinOff_Of_Business_Details

Spin-Off Of Business (Details) (USD $)	3 Months Ended	6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2013
Discontinued Operations And Disposal Groups [Abstract]
Revenues	$19.90	$40
Earnings before income taxes	2.8	5.9
Income tax expense	-2	-3.4
Earnings from discontinued operations, net of income taxes	$0.80	$2.50

Goodwill_Narrative_Details

Goodwill (Narrative) (Details) (USD $)	6 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Jun. 30, 2014
Goodwill [Line Items]
Goodwill	$868.70	$845.30
Foreign currency translation	15.5
Access and Fiberlink,LLC [Member]
Goodwill [Line Items]
Adjustment to goodwill acquired		-15.8
Dark Fiber [Member]
Goodwill [Line Items]
Adjustment to goodwill acquired		27.5
Waves
Goodwill [Line Items]
Adjustment to goodwill acquired		($27.50)

Goodwill_Schedule_Of_Goodwill_

Goodwill (Schedule Of Goodwill) (Details) (USD $)	6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Jun. 30, 2014
Goodwill [Line Items]
Goodwill	$845.30
Goodwill, Other adjustments	-15.5
Goodwill	868.7
Atlanta NAP [Member]
Goodwill [Line Items]
Goodwill	13.7
Additions	13.7
Neo [Member]
Goodwill [Line Items]
Goodwill	25.2
Additions	25.2
Dark Fiber [Member]
Goodwill [Line Items]
Goodwill	269.9
Goodwill, Other adjustments	-5.7
Goodwill	264.2
Waves
Goodwill [Line Items]
Goodwill	270
Goodwill, Other adjustments	-5.8
Goodwill	264.2
SONET [Member]
Goodwill [Line Items]
Goodwill		50.3
Goodwill	50.3	50.3
Ethernet [Member]
Goodwill [Line Items]
Goodwill	96.7
Goodwill, Other adjustments	-0.1
Goodwill	96.6
IP [Member]
Goodwill [Line Items]
Goodwill	80.4
Goodwill, Other adjustments	-0.2
Goodwill	80.2
MIG [Member]
Goodwill [Line Items]
Goodwill		43.7
Goodwill	43.7	43.7
zColo [Member]
Goodwill [Line Items]
Goodwill	19.6
Goodwill, Other adjustments	-0.9
Goodwill	32.4
zColo [Member] | Atlanta NAP [Member]
Goodwill [Line Items]
Additions	13.7
Other [Member]
Goodwill [Line Items]
Goodwill	14.7
Goodwill, Other adjustments	-2.8
Goodwill	37.1
Other [Member] | Neo [Member]
Goodwill [Line Items]
Additions	$25.20

Intangible_Assets_Schedule_of_

Intangible Assets (Schedule of Intangible Assets) (Details) (USD $)	Dec. 31, 2014	Jun. 30, 2014
In Millions, unless otherwise specified
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	$823.80	$791.10
Accumulated Amortization	-125.6	-104.3
Total Net	698.2	686.8
Intangible Assets, Gross (Excluding Goodwill)	845	814
Intangible Assets, Net	719.4	709.7
Customer relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	822	789.2
Accumulated Amortization	-125.5	-104.2
Total Net	696.5	685
Trade names [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	0.1	0.1
Total Net	0.1	0.1
Underlying rights [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	1.7	1.8
Accumulated Amortization	-0.1	-0.1
Total Net	1.6	1.7
Certifications [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, Indefinite-lived Intangibles	3.5	3.5
Easement indefinite [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount, Indefinite-lived Intangibles	$17.70	$19.40

LongTerm_Debt_Summary_of_LongT

Long-Term Debt (Summary of Long-Term Debt) (Details) (USD $)	Dec. 31, 2014	Jun. 30, 2014	16-May-14	Mar. 31, 2014
In Millions, unless otherwise specified
Debt Instrument [Line Items]
Debt obligations	$3,001.10	$3,260.80		$1,749.80
Unamortized discount on Term Loan Facility due 2019	-18.7	-20.6
Carrying value of debt	2,982.40	3,240.20	2,015.90
Less current portion	-20.5	-20.5
Long-term debt, less current portion	2,961.90	3,219.70
Term Loan Facility due 2019 [Member] | Credit Facility [Member]
Debt Instrument [Line Items]
Debt obligations	2,000.50	2,010.80
Secured Debt [Member] | 8.125% Senior Secured First Priority Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt obligations	675	750
Unsecured Debt [Member] | 10.125% Senior Unsecured Notes due 2020 [Member]
Debt Instrument [Line Items]
Debt obligations	$325.60	$500

LongTerm_Debt_Narrative_Detail

Long-Term Debt (Narrative) (Details) (USD $)	0 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended	3 Months Ended	0 Months Ended
In Millions, unless otherwise specified	16-May-14	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2014	Mar. 31, 2014	Jul. 02, 2012	Aug. 13, 2012	Dec. 15, 2014
Debt Instrument [Line Items]
Discount on debt		$18.70		$18.70		$20.60
Debt obligations		3,001.10		3,001.10		3,260.80	1,749.80
Debt issuance cost				105.5
Loss on extinguishment of debt		-30.9	-1.9	-30.9	-1.9
Debt instrument carrying amount	2,015.90	2,982.40		2,982.40		3,240.20
Debt instrument, call feature	99.50%
Redemption premium		23.8		23.8
Unamortized debt issuance cost		74.7		74.7		89.4
Accretion of premium on debt				30.8		25.4
Unamortized debt issuance related interest		3.8	3.4	7.5	6.8
Interest Rate Swap [Member]
Debt Instrument [Line Items]
Notional amount of derivative									750
Derivative, maturity date				30-Jun-17
Derivative, fixed interest rate									1.67%
Derivative, floor rate									1.25%
Change in fair value of interest rate swap		1.5	-0.4	-0.5	1.9
Interest Rate Derivative Assets, at Fair Value		1.5		1.5		2
payment on interest rate derivatives		0.8	0.8	1.6	1.6
Senior Secured And Senior Unsecured Notes
Debt Instrument [Line Items]
Loss on extinguishment of debt		-7.1		-7.1
Fifth Amendment [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt							150
Sixth Amendment [Member]
Debt Instrument [Line Items]
Proceeds from Issuance of Long-term Debt	275
Senior Secured Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount								750
Debt instrument, interest rate								8.13%		8.13%
Debt Instrument Maturity Year								2020
Redemption of notes										75
Redemption price as percentage										108.13%
Senior Unsecured Notes [Member]
Debt Instrument [Line Items]
Debt instrument, face amount								500
Debt instrument, interest rate								10.13%		10.13%
Debt Instrument Maturity Year								2020
Redemption of notes										174.4
Redemption price as percentage										110.13%
Revolver [Member]
Debt Instrument [Line Items]
Debt instrument, face amount								250
Revolver [Member] | Fifth Amendment [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Percentage over variable rate						2.75%
Term Loan Facility [Member]
Debt Instrument [Line Items]
Discount on debt								30
Payment towards principal				5.1
Percentage of excess cash flows committed to debt payments				50.00%
Debt instrument, maturity date				31-Jul-19
Debt obligations		1,981.80		1,981.80		1,990.20
Percentage over variable rate		4.00%		4.00%		4.00%
Term Loan Facility [Member] | LIBOR [Member] | Maximum
Debt Instrument [Line Items]
Revolver interest rate		3.00%
Term Loan Facility [Member] | LIBOR [Member] | Minimum [Member]
Debt Instrument [Line Items]
Percentage over variable rate						1.00%
Term Loan Facility [Member] | Fourth Amendment
Debt Instrument [Line Items]
Interest rate decrease		0.25%
Term Loan Facility [Member] | Fourth Amendment | Minimum [Member]
Debt Instrument [Line Items]
Interest rate decrease		0.50%
New Term Loan Facility [Member] | Fifth Amendment [Member]
Debt Instrument [Line Items]
Debt issuance cost		1.5
Loss on extinguishment of debt		-1.9
New Term Loan Facility [Member] | Fifth Amendment [Member] | Third Party Costs Cash Expense [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt		-1
New Term Loan Facility [Member] | Fifth Amendment [Member] | Unamortized Debt Issuance Costs And Discount On Debt [Member]
Debt Instrument [Line Items]
Loss on extinguishment of debt		-0.9
Original Revolver [Member]
Debt Instrument [Line Items]
Percentage over variable rate		3.00%		3.00%		3.00%
Outstanding letters of credit		0		0
Available borrowing capacity		241.4		241.4
Unused commitment, percentage				0.50%
Debt instrument, maturity date				7/31/17
Standby Letter Of Credit [Member]
Debt Instrument [Line Items]
Outstanding letters of credit		$8.60		$8.60
Unused commitment, percentage				0.25%

LongTerm_Debt_Schedule_of_Fixe

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

Income_Taxes_Schedule_Of_Provi

Income Taxes (Schedule Of Provision For Income Tax) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Current income taxes
Federal income taxes - current	$1.60		$3.10
State income taxes - current	0.9	1.3	1.8	2.1
Foreign income taxes- current			0.8
Current Income Tax Expense (Benefit), Total	2.5	1.3	5.7	2.1
Deferred income taxes
Federal income taxes - deferred	-5.3	6.1	1	13
State income taxes - deferred	-1.4	-0.5	-1.2	-0.3
Foreign income taxes deferred	-0.2	1.5	-0.5	2.9
Deferred Income Tax Expense (Benefit), Total	-6.9	7.1	-0.7	15.6
Total (benefit)/provision for income taxes	($4.40)	$8.40	$5	$17.70

Income_Taxes_IncomeLoss_from_C

Income Taxes (Income/(Loss) from Continuing Operations Before Income Tax) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
United States	$0.10	($32.10)	($92.50)	($56.40)
Foreign	-0.7	2.9	-9.2	7.4
Loss from operations before income taxes	($0.60)	($29.20)	($101.70)	($49)

Income_Taxes_Schedule_Of_Recon

Income Taxes (Schedule Of Reconciliation Of Income Tax Provision) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Expected benefit at statutory rate	($0.30)	($10.10)	($35.60)	($17)
Non-deductible stock-based compensation	-5.1	22.5	42.1	39.5
State income taxes (benefit)/provision, net of federal benefit		-1.6	-4.5	-2.8
Transaction costs not deductible for tax purposes	0.1	-0.1	0.4	0.1
Foreign tax rate differential	-0.3	-0.4	0.8	-1
Release of accrual for uncertain tax position		-2.6		-2.6
Other, net	1.2	0.7	1.8	1.5
Total (benefit)/provision for income taxes	($4.40)	$8.40	$5	$17.70

Equity_Details

Equity (Details) (USD $)	0 Months Ended	6 Months Ended
In Millions, except Share data, unless otherwise specified	Oct. 22, 2014	Dec. 31, 2014	Oct. 10, 2014	Oct. 09, 2014	Jun. 30, 2014	Oct. 20, 2014	Oct. 16, 2014
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Common stock, shares issued		239,008,679			223,000,000
Common stock, par value		$0.00	$0.00		$0.00
Authorized stock split		On October 9, 2014, the Board of Directors approved a 223,000-for-one stock split of the Company's common stock.
Common stock, shares outstanding		239,008,679	223,000,000	223,000,000	223,000,000
Common stock shares issued as initial public offering	16,008,679
Common stock issuance costs		$22.20
Proceeds from issuance of common stock (net of issuance costs)		282
Note receivable from shareholder
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Non-cash settlement of note receivable from Communications Infrastructure Investments, LLC (Note 8)		22
Additional paid-in Capital [Member]
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Proceeds from issuance of common stock (net of issuance costs)		282
Non-cash settlement of note receivable from Communications Infrastructure Investments, LLC (Note 8)		-22
IPO
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Common stock shares issued as initial public offering	24,079,002	16,008,679
Shares Issued, Price Per Share			$19			$19
Net proceeds from IPO, after deducting underwriting discounts and other offering expenses.	282	304.2
Common stock issuance costs		22.2
CII [Member]
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Common stock, shares issued							1,000
Common stock, par value							$0.00
CII [Member] | Note receivable from shareholder
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Non-cash settlement of note receivable from Communications Infrastructure Investments, LLC (Note 8)		22
CII [Member] | Additional paid-in Capital [Member]
Deferred Compensation Arrangement With Individual Excluding Share Based Payments And Postretirement Benefits [Line Items]
Non-cash settlement of note receivable from Communications Infrastructure Investments, LLC (Note 8)		$22

StockBased_Compensation_Summar

Stock-Based Compensation (Summary of Stock-based Compensation Expense Liability and Equity Classified Awards Included on the Consolidated Statements of Operations) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	($6)	$57	$117.10	$99.90
Operating Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	0.9	4.3	15.4	8
Selling, General and Administrative Expenses [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	-6.9	52.7	101.7	91.9
Part A Restricted Stock Units
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	2.6		2.6
Part B Restricted Stock Units
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	4.7		4.7
CII [Member] | Common Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	-13.4	56.9	109.6	99.6
CII [Member] | Preferred Units [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$0.10	$0.10	$0.20	$0.30

StockBased_Compensation_Narrat

Stock-Based Compensation (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended		0 Months Ended			3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Oct. 16, 2014	Oct. 09, 2014	Sep. 17, 2014	Sep. 30, 2014	Dec. 31, 2014	Jun. 30, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Reclassification of common unit liability to additional paid in capital			$490,200,000
Vesting date			15-May-17
Common stock distributed in connection with non-liquidating distribution	239,008,679		239,008,679						239,008,679	223,000,000
Total stock-based compensation expense	-6,000,000	57,000,000	117,100,000	99,900,000
PCIP [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incentive plan termination period					10 years
CII [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized	625,000,000		625,000,000						625,000,000
Unrecognized compensation cost	124,100,000		124,100,000						124,100,000
Common stock distributed in connection with non-liquidating distribution					1,000
Common stock distributed in exchange for vested preferred units						256,265
CII [Member] | Common Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock distributed in connection with non-liquidating distribution						20,460,047
Common unit unvested						6,392,071
Common stock distributed for existing share holders						10,294,867
Total stock-based compensation expense	-13,400,000	56,900,000	109,600,000	99,600,000
CII [Member] | Preferred Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	100,000	100,000	200,000	300,000
Part A Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs outstanding	146,001		146,001						146,001
Unrecognized compensation cost	10,200,000		10,200,000						10,200,000
Total stock-based compensation expense	2,600,000		2,600,000
Compensation expense associated with vested portion	2,000,000
Part A Restricted Stock Units | Dan Caruso [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation cost	2,400,000		2,400,000						2,400,000
Total stock-based compensation expense	400,000
One-time grant amount							2,800,000
One-time grant shares							144,737
Annual salary							17,500	400,000
Part B Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
RSUs outstanding	575,660		575,660						575,660
Unrecognized compensation cost	31,900,000		31,900,000						31,900,000
Common unit unvested	2,210,534		2,210,534						2,210,534
Total stock-based compensation expense	4,700,000		4,700,000
One-time grant shares	575,660
Participants eligible to earn shares									2,210,534
Grant date fair value of the awards	$36,300,000

Fair_Value_Measurements_Narrat

Fair Value Measurements (Narrative) (Details) (USD $)	6 Months Ended	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Carrying value of the notes	$3,001.10	$3,001.10				$3,260.80	$1,749.80
Hypothetical annual interest expense	20
Hypothetical increase to interest rate swap fair value					14
Interest Rate Swap [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Hypothetical interest rate increase		1.00%
Change in fair value of interest rate swap	-0.5	1.5	-0.4	1.9
Term Loan Facility [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Carrying value of the notes	1,981.80	1,981.80				1,990.20
Floor rate	1.00%
Debt Instrument, Interest Rate, Stated Percentage Rate Range, Maximum	3.00%
Hypothetical interest rate increase	1.00%
Notes [Member]
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items]
Carrying value of the notes	1,000.60	1,000.60				1,250
Fair value of the notes	$1,083.10	$1,083.10				$1,294.80

Fair_Value_Measurements_Schedu

Fair Value Measurements (Schedule Of Financial Instruments Measured At Fair Value On A Recurring Basis) (Details) (USD $)	Dec. 31, 2014	Jun. 30, 2014
In Millions, unless otherwise specified
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Interest Rate Derivative Liabilities, at Fair Value	$1.50	$2
Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Stock-based compensation liability	$2	$392.40

Commitments_and_Contingencies_

Commitments and Contingencies (Narrative) (Details) (USD $)	Dec. 31, 2014
In Millions, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]
Purchase commitments	$128.90

Related_Party_Transactions_Sch

Related Party Transactions (Schedule of Transactions Recognized ) (Details) (O V S, USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
O V S
Related Party Transaction [Line Items]
Revenues	$1.70	$1.70	$3.40	$3.40
Operating costs	($0.40)	($0.40)	($0.70)	($0.80)

Related_Party_Transactions_Nar

Related Party Transactions (Narrative) (Details) (USD $)	3 Months Ended				6 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2014
Related Party Transaction [Line Items]
Due from related parties	$0.10
O V S
Related Party Transaction [Line Items]
Due from related parties	0.1			0	0
CII [Member]
Related Party Transaction [Line Items]
Authorized non-liquidating cash distribution			10
Non-liquidating distribution to common unit holders made by subsidiary to parent company	9.1	3	10
Non-cash settlement of note receivable from stock holder	22
Dan Caruso [Member] | Aircraft Reimbursement [Member]
Related Party Transaction [Line Items]
Payable to related party settled				$0.20	$0.60

Segment_Reporting_Narrative_De

Segment Reporting (Narrative) (Details)	3 Months Ended
	Sep. 30, 2014
	segments
Segment Reporting Information [Line Items]
Contract term	1 year
Number of reportable segments	3
Physical Infrastructure [Member] | Minimum [Member]
Segment Reporting Information [Line Items]
Contract term	3 years
Physical Infrastructure [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	20 years
Lit Services [Member] | Minimum [Member]
Segment Reporting Information [Line Items]
Contract term	2 years
Lit Services [Member] | Maximum
Segment Reporting Information [Line Items]
Contract term	5 years

Segment_Reporting_Summary_of_S

Segment Reporting (Summary of Significant Financial Information) (Details) (USD $)	3 Months Ended		6 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2014
Segment Reporting Information [Line Items]
Revenue from external customers	$323.90	$277	$644.50	$545.10
Segment Adjusted EBITDA	189.7	161.7	372.7	317.3
Total assets	5,063.90		5,063.90		5,050.40
Capital expenditures	129.5	88.3	244.8	175
Interest expense	-53.4	-50.3	-100.3	-101.8
Benefit/(provision) for income taxes	4.4	-8.4	-5	-17.7
Depreciation and amortization expense	-96.9	-81.7	-192.9	-162.7
Transaction costs	-1.3	-0.2	-4.8	-0.8
Stock-based compensation	6	-57	-117.1	-99.9
Loss on extinguishment of debt	-30.9	-1.9	-30.9	-1.9
Foreign currency loss on intercompany loans	-13.3	0.2	-27.9	0.8
Non-cash loss on investments	-0.5		-0.5
Income/(loss) from continuing operations	3.8	-37.6	-106.7	-66.7
Reportable Segments [Member] | Physical Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	152.7	120.9	302.4	234.5
Segment Adjusted EBITDA	102.1	80.2	199.4	154.5
Total assets	2,878.50		2,878.50		2,851.80
Capital expenditures	76.6	46.7	144.6	91.9
Reportable Segments [Member] | Lit Services [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	157.4	151.3	313.5	300.7
Segment Adjusted EBITDA	84.2	81.1	166.4	161.9
Total assets	1,781.80		1,781.80		1,739.10
Capital expenditures	52.5	41.6	98.5	83.1
Reportable Segments [Member] | Other [Member]
Segment Reporting Information [Line Items]
Revenue from external customers	13.8	6.5	28.6	13.3
Segment Adjusted EBITDA	3.4	1.8	6.9	3.6
Total assets	123.1		123.1		43.1
Capital expenditures	0.4		1.7
Corporate/eliminations [Member]
Segment Reporting Information [Line Items]
Revenue from external customers		-1.7		-3.4
Segment Adjusted EBITDA		-1.4		-2.7
Total assets	$280.50		$280.50		$416.40

Subsequent_Events_Details

Subsequent Events (Details) (Subsequent Event [Member], USD $)	0 Months Ended
In Millions, unless otherwise specified	Jan. 23, 2015	Jan. 02, 2015	Jan. 13, 2015
		Buildings	MW
		mi	sqft
		CellularTowers
Senior Unsecured Notes due 2023 [Member]
Subsequent Event [Line Items]
Debt instrument, face amount	$700
Debt instrument, interest rate	6.00%
Debt instrument, maturity date	1-Apr-23
Senior Unsecured Notes due 2023 [Member] | Debt redemption in whole before April 1, 2018 [Member]
Subsequent Event [Line Items]
Debt instrument, redemption price, percentage	100.00%
Senior Unsecured Notes due 2023 [Member] | Debt redemption in part before April 1, 2018 [Member]
Subsequent Event [Line Items]
Debt instrument, redemption price, percentage	106.00%
Debt instrument, percentage of principal amount redeemed	40.00%
Acquisition Of IdeaTek [Member]
Subsequent Event [Line Items]
Acquisition date		1-Jan-15
Consideration of acquiring equity ownership		52
Additional route miles added		1,800
Number of additional cellular towers added		600
Number of additional building added		100
Pending Acquisition Of Latisys [Member]
Subsequent Event [Line Items]
Business combination, recognized identifiable assets acquired and liabilities assumed, net			$675
Acquired area in square feet			185,000
Critical power acquired			33