Goodwill (Schedule Of Goodwill) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Sep. 30, 2014	Jun. 30, 2014
Goodwill		$ 845.3
Goodwill, Other adjustments	(7.8)
Goodwill	874.3	845.3
Atlanta NAP [Member]
Goodwill		13.6
Additions	13.6
Goodwill		13.6
Neo [Member]
Goodwill		25.0
Additions	23.2
Goodwill		25.0
Dark Fiber [Member]
Goodwill		269.9
Goodwill, Other adjustments	(4.4)
Goodwill	265.5	269.9
Waves [Member]
Goodwill		270.0
Goodwill, Other adjustments	(3.4)
Goodwill	266.6	270.0
SONET [Member]
Goodwill		50.3
Goodwill	50.3	50.3
Ethernet [Member]
Goodwill		96.7
Goodwill, Other adjustments	(0.1)
Goodwill	96.6	96.7
IP [Member]
Goodwill		80.4
Goodwill, Other adjustments	(0.1)
Goodwill	80.3	80.4
MIG [Member]
Goodwill		43.7
Goodwill	43.7	43.7
zColo [Member]
Goodwill		19.6
Goodwill, Other adjustments	0.2
Goodwill	33.4	19.6
zColo [Member] | Atlanta NAP [Member]
Additions	13.6
Other [Member]
Goodwill		14.7
Goodwill	37.9	14.7
Other [Member] | Neo [Member]
Additions	$ 23.2