Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Revenue	$ 310.8	$ 368.2	$ 948.5	$ 1,099.2
Operating income	57.7	66.0	123.7	212.2
Expenditures for long-lived assets	46.1	75.5	142.0	242.9
Depreciation and amortization	39.8	55.4	127.6	160.2
Assets	2,551.7		2,551.7		2,872.4
Segment Reporting Information, Additional Information [Abstract]
Total ownership interests in CyrusOne, Percentage	69.00%		69.00%
Loss from CyrusOne	1.5	0	8.1	0
Investment in CyrusOne	480.7		480.7		0
Wireline [Member]
Segment Reporting Information [Line Items]
Revenue	181.4	182.3	542.7	548.4
Operating income	47.8	50.9	146.8	162.8
Expenditures for long-lived assets	41.2	27.8	114.3	77.5
Depreciation and amortization	29.7	26.6	83.8	78.9
Assets	766.7		766.7		723.7
Wireless [Member]
Segment Reporting Information [Line Items]
Revenue	49.1	59.5	154.1	185.0
Operating income	7.0	12.6	19.1	43.5
Expenditures for long-lived assets	2.2	4.2	12.4	12.4
Depreciation and amortization	7.4	8.1	30.7	24.0
Assets	252.2		252.2		275.6
IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	87.5	78.3	258.0	228.8
Operating income	4.4	3.8	6.6	7.2
Expenditures for long-lived assets	2.7	1.9	7.6	6.6
Depreciation and amortization	2.5	2.4	7.5	6.3
Assets	51.8		51.8		43.3
Data Center Colocation [Member]
Segment Reporting Information [Line Items]
Revenue	0	56.7	15.6	163.3
Operating income	0	11.2	3.2	22.5
Expenditures for long-lived assets	0	41.6	7.7	146.4
Depreciation and amortization	0	18.3	5.2	50.9
Assets	0		0		1,208.5
Corporate [Member]
Segment Reporting Information [Line Items]
Operating income	(1.5)	(12.5)	(52.0)	(23.8)
Depreciation and amortization	0.2	0	0.4	0.1
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(7.2)	(8.6)	(21.9)	(26.3)
Intersegment Eliminations [Member] | Wireline [Member]
Segment Reporting Information [Line Items]
Revenue	4.2	4.8	12.8	14.5
Intersegment Eliminations [Member] | Wireless [Member]
Segment Reporting Information [Line Items]
Revenue	0.5	0.5	1.7	1.7
Intersegment Eliminations [Member] | IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	2.5	1.8	7.0	5.4
Intersegment Eliminations [Member] | Data Center Colocation [Member]
Segment Reporting Information [Line Items]
Revenue	0	1.5	0.4	4.7
Intersegment Eliminations [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Assets	1,481.0		1,481.0		621.3
Sales [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	$ 7.2	$ 8.6	$ 21.9	$ 26.3