Business Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Number of Operating Segments	3		4
Investment in CyrusOne	$ 284.7			$ 284.7		$ 471.0
Indefinite-lived Intangible Assets, Period Decrease	88.2
Revenue	327.5	310.8		969.9	948.5
Operating income (loss)	16.0	57.7		108.5	123.7
Expenditures for long-lived assets	45.6	46.1		121.1	142.0
Depreciation and amortization	61.4	39.8		168.6	127.6
Assets	1,952.6			1,952.6		2,107.3
Wireline [Member]
Segment Reporting Information [Line Items]
Revenue	184.0	181.4		552.3	542.7
Operating income (loss)	43.9	47.8		147.0	146.8
Expenditures for long-lived assets	41.8	41.2		106.1	114.3
Depreciation and amortization	29.3	29.7		85.6	83.8
Assets	819.7			819.7		780.8
IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	120.0	87.5		323.5	258.0
Operating income (loss)	8.1	4.4		16.3	6.6
Expenditures for long-lived assets	3.5	2.7		8.5	7.6
Depreciation and amortization	3.0	2.5		8.6	7.5
Assets	58.2			58.2		48.9
Wireless [Member]
Segment Reporting Information [Line Items]
Proceeds from sale of Wireless spectrum licenses	194.4
Indefinite-lived Intangible Assets, Period Decrease	88.2
Revenue	30.1	49.1		116.0	154.1
Operating income (loss)	(33.0)	7.0		(40.8)	19.1
Expenditures for long-lived assets	0.3	2.2		6.5	12.4
Depreciation and amortization	29.1	7.4		74.2	30.7
Assets	148.0			148.0		247.5
Data Center Colocation [Member]
Segment Reporting Information [Line Items]
Revenue	0	0		0	15.6
Operating income (loss)	0	0		0	3.2
Expenditures for long-lived assets	0	0		0	7.7
Depreciation and amortization	0	0		0	5.2
Corporate [Member]
Segment Reporting Information [Line Items]
Operating income (loss)	(3.0)	(1.5)		(14.0)	(52.0)
Depreciation and amortization	0	0.2		0.2	0.4
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	(6.6)	(7.2)		(21.9)	(21.9)
Intersegment Eliminations [Member] | Wireline [Member]
Segment Reporting Information [Line Items]
Revenue	3.9	4.2		12.0	12.8
Intersegment Eliminations [Member] | IT Services and Hardware [Member]
Segment Reporting Information [Line Items]
Revenue	2.3	2.5		8.4	7.0
Intersegment Eliminations [Member] | Wireless [Member]
Segment Reporting Information [Line Items]
Revenue	0.4	0.5		1.5	1.7
Intersegment Eliminations [Member] | Data Center Colocation [Member]
Segment Reporting Information [Line Items]
Revenue	0	0		0	0.4
Intersegment Eliminations [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Assets	926.7			926.7		1,030.1
Sales [Member] | Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenue	$ 6.6	$ 7.2		$ 21.9	$ 21.9