Supplemental Guarantor Information HY (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Abstract]
Revenue	$ 308.4	$ 310.8	$ 312.0	$ 325.7	$ 374.7	$ 368.2	$ 368.2	$ 362.8	$ 1,256.9	$ 1,473.9	$ 1,462.4
Operating costs and expenses									1,093.1	1,203.8	1,202.9
Operating income (loss)	40.1	57.7	46.8	19.2	57.9	66.0	65.2	81.0	163.8	270.1	259.5
Interest expense (income), net									182.0	218.9	215.0
Other expense (income), net									(1.3)	1.7	0.9
(Loss) income before equity in earnings of subsidiaries and income taxes									(57.2)	35.9	43.6
Income tax (benefit) expense									(2.5)	24.7	25.0
Net (loss) income	(28.1)	9.3	0.8	(36.7)	(9.8)	3.9	4.5	12.6	(54.7)	11.2	18.6
Other comprehensive income (loss)									76.4	(0.8)	(48.9)
Total comprehensive income (loss)									21.7	10.4	(30.3)
Preferred stock dividends									10.4	10.4	10.4
Net (loss) income applicable to common shareowners									(65.1)	0.8	8.2
Condensed Consolidating Balance Sheets [Abstract]
Cash and cash equivalents	4.6				23.6				4.6	23.6	73.7
Other current assets	1.6				11.6				1.6	11.6
Total current assets	251.1				303.5				251.1	303.5
Property, plant and equipment, net	902.8				1,587.4				902.8	1,587.4
Investment in CyrusOne	471.0				0				471.0	0
Other noncurrent assets	36.6				86.3				36.6	86.3
Total assets	2,107.3				2,872.4				2,107.3	2,872.4
Current portion of long-term debt	12.6				13.4				12.6	13.4
Accounts payable	89.4				135.6				89.4	135.6
Other current liabilities	36.8				40.2				36.8	40.2
Total current liabilities	254.3				355.4				254.3	355.4
Long-term debt, less current portion	2,252.6				2,676.0				2,252.6	2,676.0
Other noncurrent liabilities	74.4				176.5				74.4	176.5
Total liabilities	2,784.0				3,570.6				2,784.0	3,570.6
Shareowners' (deficit) equity	(676.7)				(698.2)				(676.7)	(698.2)	(715.2)	(667.8)
Total liabilities and shareowners' equity (deficit)	2,107.3				2,872.4				2,107.3	2,872.4
Condensed Consolidating Statements of Cash Flows [Abstract]
Cash flows (used in) provided by operating activities									78.8	212.7	289.9
Capital expenditures									(196.9)	(367.2)	(255.5)
Dividends received from CyrusOne									21.3	0	0
Proceeds from sale of assets									2.0	1.6	11.5
Cash divested from deconsolidation of CyrusOne									(12.2)	0	0
Other investing activities									0	0	(0.7)
Cash flows provided by (used in) investing activities									(185.4)	(371.8)	(244.7)
Proceeds from issuance of long-term debt									536.0	525.0	0
Debt issuance costs									(6.7)	(20.9)	(0.8)
Net increase in corporate credit and receivables facilities with initial maturities less than 90 days									94.2	52.0	0.4
Repayment of debt									(530.8)	(442.4)	(11.5)
Common stock issuance costs									0	(5.7)	0
Common stock repurchase									0	(0.3)	(10.4)
Proceeds from exercise of options and warrants									7.1	12.1	0.4
Other financing activities									(2.3)	(2.8)	(16.5)
Cash flows provided by (used in) financing activities									87.6	109.0	(48.8)
(Decrease) increase in cash and cash equivalents									(19.0)	(50.1)	(3.6)
Cash and cash equivalents at beginning of year				23.6				73.7	23.6	73.7	77.3
Cash and cash equivalents at end of year	4.6				23.6				4.6	23.6	73.7
Notes guaranteed by subsidiaries [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Abstract]
Revenue									1,256.9	1,473.9	1,462.4
Operating costs and expenses									1,093.1	1,203.8	1,202.9
Operating income (loss)									163.8	270.1	259.5
Interest expense (income), net									182.0	218.9	215.0
Other expense (income), net									39.0	15.3	0.9
(Loss) income before equity in earnings of subsidiaries and income taxes									(57.2)	35.9	43.6
Income tax (benefit) expense									(2.5)	24.7	25.0
Equity in earnings of subsidiaries, net of tax									0	0	0
Net (loss) income									(54.7)	11.2	18.6
Other comprehensive income (loss)									76.4	(0.8)	(48.9)
Total comprehensive income (loss)									21.7	10.4	(30.3)
Preferred stock dividends									10.4	10.4	10.4
Net (loss) income applicable to common shareowners									(65.1)	0.8	8.2
Condensed Consolidating Balance Sheets [Abstract]
Cash and cash equivalents	4.6				23.6				4.6	23.6	73.7
Receivables, net	154.8				199.0				154.8	199.0
Other current assets	91.7				80.9				91.7	80.9
Total current assets	251.1				303.5				251.1	303.5
Property, plant and equipment, net	902.8				1,587.4				902.8	1,587.4
Investment in CyrusOne	471.0								471.0
Goodwill and intangibles, net	106.1				487.4				106.1	487.4
Investments in and advances to subsidiaries	0				0				0	0
Other noncurrent assets	376.3				494.1				376.3	494.1
Total assets	2,107.3				2,872.4				2,107.3	2,872.4
Current portion of long-term debt	12.6				13.4				12.6	13.4
Accounts payable	89.9				135.6				89.9	135.6
Other current liabilities	151.8				206.4				151.8	206.4
Total current liabilities	254.3				355.4				254.3	355.4
Long-term debt, less current portion	2,252.6				2,676.0				2,252.6	2,676.0
Other noncurrent liabilities	277.1				539.2				277.1	539.2
Intercompany payables	0				0				0	0
Total liabilities	2,784.0				3,570.6				2,784.0	3,570.6
Shareowners' (deficit) equity	(676.7)				(698.2)				(676.7)	(698.2)
Total liabilities and shareowners' equity (deficit)	2,107.3				2,872.4				2,107.3	2,872.4
Condensed Consolidating Statements of Cash Flows [Abstract]
Cash flows (used in) provided by operating activities									78.8	212.7	289.9
Capital expenditures									(196.9)	(367.2)	(255.5)
Dividends received from CyrusOne									21.3
Proceeds from sale of assets									2.0	1.6	11.5
Cash divested from deconsolidation of CyrusOne									(12.2)
Other investing activities									0.4	(6.2)	(0.7)
Cash flows provided by (used in) investing activities									(185.4)	(371.8)	(244.7)
Proceeds from issuance of long-term debt									536.0	525.0
Funding between Parent and subsidiaries, net									0	0	0
Debt issuance costs									(6.7)	(20.9)
Net increase in corporate credit and receivables facilities with initial maturities less than 90 days									94.2	52.0	0.4
Repayment of debt									(530.8)	(442.4)	(11.5)
Common stock issuance costs										(5.7)
Common stock repurchase										(0.3)	(10.4)
Proceeds from exercise of options and warrants									7.1	12.1
Other financing activities									(12.2)	(10.8)	(27.3)
Cash flows provided by (used in) financing activities									87.6	109.0	(48.8)
(Decrease) increase in cash and cash equivalents									(19.0)	(50.1)	(3.6)
Cash and cash equivalents at beginning of year				23.6				73.7	23.6	73.7	77.3
Cash and cash equivalents at end of year	4.6				23.6				4.6	23.6	73.7
Notes guaranteed by subsidiaries [Member] | Parent Company [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Abstract]
Revenue									0	0	3.4
Operating costs and expenses									55.4	33.9	23.6
Operating income (loss)									(55.4)	(33.9)	(20.2)
Interest expense (income), net									164.3	164.8	161.8
Other expense (income), net									28.2	11.5	(0.9)
(Loss) income before equity in earnings of subsidiaries and income taxes									(247.9)	(210.2)	(181.1)
Income tax (benefit) expense									(79.8)	(68.3)	(56.4)
Equity in earnings of subsidiaries, net of tax									113.4	153.1	143.3
Net (loss) income									(54.7)	11.2	18.6
Other comprehensive income (loss)									76.5	(0.8)	(48.8)
Total comprehensive income (loss)									21.8	10.4	(30.2)
Preferred stock dividends									10.4	10.4	10.4
Net (loss) income applicable to common shareowners									(65.1)	0.8	8.2
Condensed Consolidating Balance Sheets [Abstract]
Cash and cash equivalents	2.1				3.8				2.1	3.8	69.6
Receivables, net	2.6				1.0				2.6	1.0
Other current assets	4.4				3.1				4.4	3.1
Total current assets	9.1				7.9				9.1	7.9
Property, plant and equipment, net	0.1				0.1				0.1	0.1
Investment in CyrusOne	0								0
Goodwill and intangibles, net	0				0				0	0
Investments in and advances to subsidiaries	1,406.6				1,449.9				1,406.6	1,449.9
Other noncurrent assets	359.1				384.6				359.1	384.6
Total assets	1,774.9				1,842.5				1,774.9	1,842.5
Current portion of long-term debt	5.4				0				5.4	0
Accounts payable	1.5				1.2				1.5	1.2
Other current liabilities	67.7				85.6				67.7	85.6
Total current liabilities	74.6				86.8				74.6	86.8
Long-term debt, less current portion	1,916.1				1,841.7				1,916.1	1,841.7
Other noncurrent liabilities	214.5				383.3				214.5	383.3
Intercompany payables	246.4				228.9				246.4	228.9
Total liabilities	2,451.6				2,540.7				2,451.6	2,540.7
Shareowners' (deficit) equity	(676.7)				(698.2)				(676.7)	(698.2)
Total liabilities and shareowners' equity (deficit)	1,774.9				1,842.5				1,774.9	1,842.5
Condensed Consolidating Statements of Cash Flows [Abstract]
Cash flows (used in) provided by operating activities									(218.1)	(144.8)	(139.6)
Capital expenditures									0	0	0
Dividends received from CyrusOne									0
Proceeds from sale of assets									0	0	11.5
Cash divested from deconsolidation of CyrusOne									0
Other investing activities									0	0	(0.7)
Cash flows provided by (used in) investing activities									0	0	10.8
Proceeds from issuance of long-term debt									536.0	0
Funding between Parent and subsidiaries, net									174.2	433.6	150.3
Debt issuance costs									(6.7)	(3.6)
Net increase in corporate credit and receivables facilities with initial maturities less than 90 days									40.0	0	0
Repayment of debt									(522.0)	(352.0)	0
Common stock issuance costs										0
Common stock repurchase										(0.3)	(10.4)
Proceeds from exercise of options and warrants									7.1	12.1
Other financing activities									(12.2)	(10.8)	(11.3)
Cash flows provided by (used in) financing activities									216.4	79.0	128.6
(Decrease) increase in cash and cash equivalents									(1.7)	(65.8)	(0.2)
Cash and cash equivalents at beginning of year				3.8				69.6	3.8	69.6	69.8
Cash and cash equivalents at end of year	2.1				3.8				2.1	3.8	69.6
Notes guaranteed by subsidiaries [Member] | Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Abstract]
Revenue									704.6	713.4	741.6
Operating costs and expenses									667.5	646.5	714.0
Operating income (loss)									37.1	66.9	27.6
Interest expense (income), net									14.9	7.8	9.7
Other expense (income), net									17.4	9.1	9.7
(Loss) income before equity in earnings of subsidiaries and income taxes									4.8	50.0	8.2
Income tax (benefit) expense									9.7	19.2	2.6
Equity in earnings of subsidiaries, net of tax									0.7	(11.8)	11.1
Net (loss) income									(4.2)	19.0	16.7
Other comprehensive income (loss)									0	0	0
Total comprehensive income (loss)									(4.2)	19.0	16.7
Preferred stock dividends									0	0	0
Net (loss) income applicable to common shareowners									(4.2)	19.0	16.7
Condensed Consolidating Balance Sheets [Abstract]
Cash and cash equivalents	0.3				0.3				0.3	0.3	0.7
Receivables, net	7.2				1.2				7.2	1.2
Other current assets	60.7				27.7				60.7	27.7
Total current assets	68.2				29.2				68.2	29.2
Property, plant and equipment, net	194.1				220.9				194.1	220.9
Investment in CyrusOne	471.0								471.0
Goodwill and intangibles, net	103.8				106.4				103.8	106.4
Investments in and advances to subsidiaries	(1.6)				506.4				(1.6)	506.4
Other noncurrent assets	179.9				218.5				179.9	218.5
Total assets	1,015.4				1,081.4				1,015.4	1,081.4
Current portion of long-term debt	3.0				3.9				3.0	3.9
Accounts payable	72.3				90.2				72.3	90.2
Other current liabilities	36.9				33.6				36.9	33.6
Total current liabilities	112.2				127.7				112.2	127.7
Long-term debt, less current portion	87.0				88.4				87.0	88.4
Other noncurrent liabilities	61.3				90.6				61.3	90.6
Intercompany payables	149.9				160.0				149.9	160.0
Total liabilities	410.4				466.7				410.4	466.7
Shareowners' (deficit) equity	605.0				614.7				605.0	614.7
Total liabilities and shareowners' equity (deficit)	1,015.4				1,081.4				1,015.4	1,081.4
Condensed Consolidating Statements of Cash Flows [Abstract]
Cash flows (used in) provided by operating activities									26.2	51.3	120.0
Capital expenditures									(36.1)	(30.2)	(31.2)
Dividends received from CyrusOne									21.3
Proceeds from sale of assets									0	0	0
Cash divested from deconsolidation of CyrusOne									0
Other investing activities									0	0	0
Cash flows provided by (used in) investing activities									(14.8)	(30.2)	(31.2)
Proceeds from issuance of long-term debt									0	0
Funding between Parent and subsidiaries, net									(7.4)	(16.9)	(86.6)
Debt issuance costs									0	0
Net increase in corporate credit and receivables facilities with initial maturities less than 90 days									0	0	0
Repayment of debt									(4.0)	(4.6)	(2.3)
Common stock issuance costs										0
Common stock repurchase										0	0
Proceeds from exercise of options and warrants									0	0
Other financing activities									0	0	0
Cash flows provided by (used in) financing activities									(11.4)	(21.5)	(88.9)
(Decrease) increase in cash and cash equivalents									0	(0.4)	(0.1)
Cash and cash equivalents at beginning of year				0.3				0.7	0.3	0.7	0.8
Cash and cash equivalents at end of year	0.3				0.3				0.3	0.3	0.7
Notes guaranteed by subsidiaries [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Abstract]
Revenue									608.6	822.7	774.8
Operating costs and expenses									426.5	585.6	522.7
Operating income (loss)									182.1	237.1	252.1
Interest expense (income), net									2.8	46.3	43.5
Other expense (income), net									(6.6)	(5.3)	(7.9)
(Loss) income before equity in earnings of subsidiaries and income taxes									185.9	196.1	216.5
Income tax (benefit) expense									67.6	73.8	78.8
Equity in earnings of subsidiaries, net of tax									0	0	0
Net (loss) income									118.3	122.3	137.7
Other comprehensive income (loss)									(0.1)	0	(0.1)
Total comprehensive income (loss)									118.2	122.3	137.6
Preferred stock dividends									0	0	0
Net (loss) income applicable to common shareowners									118.3	122.3	137.7
Condensed Consolidating Balance Sheets [Abstract]
Cash and cash equivalents	2.2				19.5				2.2	19.5	3.4
Receivables, net	145.0				196.8				145.0	196.8
Other current assets	27.3				50.5				27.3	50.5
Total current assets	174.5				266.8				174.5	266.8
Property, plant and equipment, net	708.6				1,366.4				708.6	1,366.4
Investment in CyrusOne	0								0
Goodwill and intangibles, net	2.3				381.0				2.3	381.0
Investments in and advances to subsidiaries	218.2				192.5				218.2	192.5
Other noncurrent assets	5.1				54.1				5.1	54.1
Total assets	1,108.7				2,260.8				1,108.7	2,260.8
Current portion of long-term debt	4.2				9.5				4.2	9.5
Accounts payable	16.1				44.2				16.1	44.2
Other current liabilities	47.1				86.3				47.1	86.3
Total current liabilities	67.4				140.0				67.4	140.0
Long-term debt, less current portion	249.5				745.9				249.5	745.9
Other noncurrent liabilities	169.9				229.7				169.9	229.7
Intercompany payables	33.2				102.6				33.2	102.6
Total liabilities	520.0				1,218.2				520.0	1,218.2
Shareowners' (deficit) equity	588.7				1,042.6				588.7	1,042.6
Total liabilities and shareowners' equity (deficit)	1,108.7				2,260.8				1,108.7	2,260.8
Condensed Consolidating Statements of Cash Flows [Abstract]
Cash flows (used in) provided by operating activities									270.7	306.2	309.5
Capital expenditures									(160.8)	(337.0)	(224.3)
Dividends received from CyrusOne									0
Proceeds from sale of assets									2.0	1.6	0
Cash divested from deconsolidation of CyrusOne									(12.2)
Other investing activities									0.4	(6.2)	0
Cash flows provided by (used in) investing activities									(170.6)	(341.6)	(224.3)
Proceeds from issuance of long-term debt									0	525.0
Funding between Parent and subsidiaries, net									(166.8)	(416.7)	(63.7)
Debt issuance costs									0	(17.3)
Net increase in corporate credit and receivables facilities with initial maturities less than 90 days									54.2	52.0	0.4
Repayment of debt									(4.8)	(85.8)	(9.2)
Common stock issuance costs										(5.7)
Common stock repurchase										0	0
Proceeds from exercise of options and warrants									0	0
Other financing activities									0	0	(16.0)
Cash flows provided by (used in) financing activities									(117.4)	51.5	(88.5)
(Decrease) increase in cash and cash equivalents									(17.3)	16.1	(3.3)
Cash and cash equivalents at beginning of year				19.5				3.4	19.5	3.4	6.7
Cash and cash equivalents at end of year	2.2				19.5				2.2	19.5	3.4
Notes guaranteed by subsidiaries [Member] | Consolidation, Eliminations [Member]
Condensed Consolidating Statements of Operations and Comprehensive Income (Loss) [Abstract]
Revenue									(56.3)	(62.2)	(57.4)
Operating costs and expenses									(56.3)	(62.2)	(57.4)
Operating income (loss)									0	0	0
Interest expense (income), net									0	0	0
Other expense (income), net									0	0	0
(Loss) income before equity in earnings of subsidiaries and income taxes									0	0	0
Income tax (benefit) expense									0	0	0
Equity in earnings of subsidiaries, net of tax									(114.1)	(141.3)	(154.4)
Net (loss) income									(114.1)	(141.3)	(154.4)
Other comprehensive income (loss)									0	0	0
Total comprehensive income (loss)									(114.1)	(141.3)	(154.4)
Preferred stock dividends									0	0	0
Net (loss) income applicable to common shareowners									(114.1)	(141.3)	(154.4)
Condensed Consolidating Balance Sheets [Abstract]
Cash and cash equivalents	0				0				0	0	0
Receivables, net	0				0				0	0
Other current assets	(0.7)				(0.4)				(0.7)	(0.4)
Total current assets	(0.7)				(0.4)				(0.7)	(0.4)
Property, plant and equipment, net	0				0				0	0
Investment in CyrusOne	0								0
Goodwill and intangibles, net	0				0				0	0
Investments in and advances to subsidiaries	(1,623.2)				(2,148.8)				(1,623.2)	(2,148.8)
Other noncurrent assets	(167.8)				(163.1)				(167.8)	(163.1)
Total assets	(1,791.7)				(2,312.3)				(1,791.7)	(2,312.3)
Current portion of long-term debt	0				0				0	0
Accounts payable	0				0				0	0
Other current liabilities	0.1				0.9				0.1	0.9
Total current liabilities	0.1				0.9				0.1	0.9
Long-term debt, less current portion	0				0				0	0
Other noncurrent liabilities	(168.6)				(164.4)				(168.6)	(164.4)
Intercompany payables	(429.5)				(491.5)				(429.5)	(491.5)
Total liabilities	(598.0)				(655.0)				(598.0)	(655.0)
Shareowners' (deficit) equity	(1,193.7)				(1,657.3)				(1,193.7)	(1,657.3)
Total liabilities and shareowners' equity (deficit)	(1,791.7)				(2,312.3)				(1,791.7)	(2,312.3)
Condensed Consolidating Statements of Cash Flows [Abstract]
Cash flows (used in) provided by operating activities									0	0	0
Capital expenditures									0	0	0
Dividends received from CyrusOne									0
Proceeds from sale of assets									0	0	0
Cash divested from deconsolidation of CyrusOne									0
Other investing activities									0	0	0
Cash flows provided by (used in) investing activities									0	0	0
Proceeds from issuance of long-term debt									0	0
Funding between Parent and subsidiaries, net									0	0	0
Debt issuance costs									0	0
Net increase in corporate credit and receivables facilities with initial maturities less than 90 days									0	0	0
Repayment of debt									0	0	0
Common stock issuance costs										0
Common stock repurchase										0	0
Proceeds from exercise of options and warrants									0	0
Other financing activities									0	0	0
Cash flows provided by (used in) financing activities									0	0	0
(Decrease) increase in cash and cash equivalents									0	0	0
Cash and cash equivalents at beginning of year				0				0	0	0	0
Cash and cash equivalents at end of year	$ 0				$ 0				$ 0	$ 0	$ 0