Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenue	$ 325.7	$ 362.8
Intersegment revenue	7.4	9.1
Operating income	19.2	81.0
Expenditures for long-lived assets	50.9	84.6
Depreciation and amortization	50.6	51.1
Assets	2,151.5		2,872.4
Segment Reporting Information, Additional Information [Abstract]
Total ownership interests in CyrusOne, Percentage	69.00%
Loss from CyrusOne	(1.9)	0
Investment in CyrusOne	500.8		0
Wireline [Member]
Segment Reporting Information [Line Items]
Revenue	179.7	182.4
Intersegment revenue	4.4	5.0
Operating income	50.1	57.2
Expenditures for long-lived assets	33.8	23.3
Depreciation and amortization	26.8	25.9
Assets	737.7		723.7
Wireless [Member]
Segment Reporting Information [Line Items]
Revenue	53.3	63.7
Intersegment revenue	0.6	0.6
Operating income	0.7	15.1
Expenditures for long-lived assets	8.2	6.3
Depreciation and amortization	16.0	7.9
Assets	264.2		275.6
IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	84.5	73.2
Intersegment revenue	2.0	1.9
Operating income	1.9	2.6
Expenditures for long-lived assets	1.2	2.2
Depreciation and amortization	2.5	1.6
Assets	50.4		43.3
Data Center Colocation [Member]
Segment Reporting Information [Line Items]
Revenue	15.6	52.6
Intersegment revenue	0.4	1.6
Operating income	3.2	13.2
Expenditures for long-lived assets	7.7	52.8
Depreciation and amortization	5.2	15.6
Assets	0		1,208.5
Intersegment Elimination [Member]
Segment Reporting Information [Line Items]
Revenue	(7.4)	(9.1)
Operating income	(36.7)	(7.1)
Depreciation and amortization	0.1	0.1
Assets	$ 1,099.2		$ 621.3