Supplemental Guarantor Information - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Condensed Consolidating Balance Sheets
Cash and cash equivalents	$ 7.9	$ 7.4	$ 13.4	$ 57.9
Other current assets	3.3	2.2
Total current assets	188.3	200.4
Property, plant and equipment, net	995.0	975.5
Investment in CyrusOne	52.8	55.5
Goodwill	14.3	14.3
Other noncurrent assets	16.8	17.8
Total assets	1,444.6	1,446.4
Current portion of long-term debt	14.8	13.8
Accounts payable	118.4	128.9
Other current liabilities	24.2	25.0
Other current liabilities from discontinued operations	2.0	5.4
Total current liabilities	252.5	259.2
Long-term debt, less current portion	1,226.0	1,223.8
Other noncurrent liabilities	36.3	36.6
Total liabilities	1,736.2	1,744.6
Shareowners' (deficit) equity	(291.6)	(298.2)
Total liabilities and shareowners' equity (deficit)	1,444.6	1,446.4
Notes guaranteed by parent [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	7.9	7.4	13.4	57.9
Receivables, net	138.5	157.1
Other current assets	41.9	35.9
Total current assets	188.3	200.4
Property, plant and equipment, net	995.0	975.5
Investment in CyrusOne	52.8	55.5
Goodwill	14.3	14.3
Investments in and advances to subsidiaries	0.0	0.0
Other noncurrent assets	194.2	200.7
Total assets	1,444.6	1,446.4
Current portion of long-term debt	14.8	13.8
Accounts payable	118.4	128.9
Other current liabilities	117.3	111.1
Other current liabilities from discontinued operations	2.0	5.4
Total current liabilities	252.5	259.2
Long-term debt, less current portion	1,226.0	1,223.8
Other noncurrent liabilities	257.7	261.6
Intercompany payables	0.0	0.0
Total liabilities	1,736.2	1,744.6
Shareowners' (deficit) equity	(291.6)	(298.2)
Total liabilities and shareowners' equity (deficit)	1,444.6	1,446.4
Notes guaranteed by parent [Member] | Parent Company [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	5.9	4.6	10.6	56.2
Receivables, net	1.3	0.7
Other current assets	2.9	1.6
Total current assets	10.1	6.9
Property, plant and equipment, net	0.4	0.3
Investment in CyrusOne	0.0	0.0
Goodwill	0.0	0.0
Investments in and advances to subsidiaries	826.0	844.6
Other noncurrent assets	215.9	207.2
Total assets	1,052.4	1,059.0
Current portion of long-term debt	5.4	5.4
Accounts payable	0.4	0.7
Other current liabilities	49.3	41.6
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	55.1	47.7
Long-term debt, less current portion	1,017.7	1,018.6
Other noncurrent liabilities	232.5	235.5
Intercompany payables	37.9	54.7
Total liabilities	1,343.2	1,356.5
Shareowners' (deficit) equity	(290.8)	(297.5)
Total liabilities and shareowners' equity (deficit)	1,052.4	1,059.0
Notes guaranteed by parent [Member] | Cincinnati Bell Telephone Company [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	1.1	1.0	1.2	1.0
Receivables, net	0.4	0.0
Other current assets	21.0	20.2
Total current assets	22.5	21.2
Property, plant and equipment, net	941.5	921.5
Investment in CyrusOne	0.0	0.0
Goodwill	2.2	2.2
Investments in and advances to subsidiaries	43.2	63.9
Other noncurrent assets	2.6	3.0
Total assets	1,012.0	1,011.8
Current portion of long-term debt	6.1	5.0
Accounts payable	83.4	84.8
Other current liabilities	45.6	45.3
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	135.1	135.1
Long-term debt, less current portion	109.5	134.3
Other noncurrent liabilities	177.5	168.3
Intercompany payables	0.0	0.0
Total liabilities	422.1	437.7
Shareowners' (deficit) equity	589.9	574.1
Total liabilities and shareowners' equity (deficit)	1,012.0	1,011.8
Notes guaranteed by parent [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.9	1.8	1.6	0.7
Receivables, net	136.8	156.4
Other current assets	18.0	14.1
Total current assets	155.7	172.3
Property, plant and equipment, net	53.1	53.7
Investment in CyrusOne	52.8	55.5
Goodwill	12.1	12.1
Investments in and advances to subsidiaries	698.4	647.2
Other noncurrent assets	130.4	136.8
Total assets	1,102.5	1,077.6
Current portion of long-term debt	3.3	3.4
Accounts payable	34.6	43.4
Other current liabilities	22.4	24.2
Other current liabilities from discontinued operations	2.0	5.4
Total current liabilities	62.3	76.4
Long-term debt, less current portion	98.8	70.9
Other noncurrent liabilities	2.4	4.0
Intercompany payables	0.0	0.0
Total liabilities	163.5	151.3
Shareowners' (deficit) equity	939.0	926.3
Total liabilities and shareowners' equity (deficit)	1,102.5	1,077.6
Notes guaranteed by parent [Member] | Consolidation, Eliminations [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.0	0.0	0.0	0.0
Receivables, net	0.0	0.0
Other current assets	0.0	0.0
Total current assets	0.0	0.0
Property, plant and equipment, net	0.0	0.0
Investment in CyrusOne	0.0	0.0
Goodwill	0.0	0.0
Investments in and advances to subsidiaries	(1,567.6)	(1,555.7)
Other noncurrent assets	(154.7)	(146.3)
Total assets	(1,722.3)	(1,702.0)
Current portion of long-term debt	0.0	0.0
Accounts payable	0.0	0.0
Other current liabilities	0.0	0.0
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	0.0	0.0
Long-term debt, less current portion	0.0	0.0
Other noncurrent liabilities	(154.7)	(146.2)
Intercompany payables	(37.9)	(54.7)
Total liabilities	(192.6)	(200.9)
Shareowners' (deficit) equity	(1,529.7)	(1,501.1)
Total liabilities and shareowners' equity (deficit)	(1,722.3)	(1,702.0)
Notes guaranteed by subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	7.9	7.4	13.4	57.9
Receivables, net	138.5	157.1
Other current assets	41.9	35.9
Total current assets	188.3	200.4
Property, plant and equipment, net	995.0	975.5
Investment in CyrusOne	52.8	55.5
Goodwill	14.3	14.3
Investments in and advances to subsidiaries	0.0	0.0
Other noncurrent assets	194.2	200.7
Total assets	1,444.6	1,446.4
Current portion of long-term debt	14.8	13.8
Accounts payable	118.4	128.9
Other current liabilities	117.3	111.1
Other current liabilities from discontinued operations	2.0	5.4
Total current liabilities	252.5	259.2
Long-term debt, less current portion	1,226.0	1,223.8
Other noncurrent liabilities	257.7	261.6
Intercompany payables	0.0	0.0
Total liabilities	1,736.2	1,744.6
Shareowners' (deficit) equity	(291.6)	(298.2)
Total liabilities and shareowners' equity (deficit)	1,444.6	1,446.4
Notes guaranteed by subsidiaries [Member] | Parent Company [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	5.9	4.6	10.6	56.2
Receivables, net	1.3	0.7
Other current assets	2.9	1.6
Total current assets	10.1	6.9
Property, plant and equipment, net	0.4	0.3
Investment in CyrusOne	0.0	0.0
Goodwill	0.0	0.0
Investments in and advances to subsidiaries	826.0	844.6
Other noncurrent assets	215.9	207.2
Total assets	1,052.4	1,059.0
Current portion of long-term debt	5.4	5.4
Accounts payable	0.4	0.7
Other current liabilities	49.3	41.6
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	55.1	47.7
Long-term debt, less current portion	1,017.7	1,018.6
Other noncurrent liabilities	232.5	235.5
Intercompany payables	37.9	54.7
Total liabilities	1,343.2	1,356.5
Shareowners' (deficit) equity	(290.8)	(297.5)
Total liabilities and shareowners' equity (deficit)	1,052.4	1,059.0
Notes guaranteed by subsidiaries [Member] | Guarantor Subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.2	0.4	0.3	0.2
Receivables, net	3.1	2.8
Other current assets	19.0	15.6
Total current assets	22.3	18.8
Property, plant and equipment, net	52.8	53.4
Investment in CyrusOne	52.8	55.5
Goodwill	12.1	12.1
Investments in and advances to subsidiaries	822.4	830.4
Other noncurrent assets	126.9	133.4
Total assets	1,089.3	1,103.6
Current portion of long-term debt	3.3	3.4
Accounts payable	71.4	95.6
Other current liabilities	25.1	26.8
Other current liabilities from discontinued operations	2.0	5.4
Total current liabilities	101.8	131.2
Long-term debt, less current portion	52.3	53.3
Other noncurrent liabilities	10.3	11.8
Intercompany payables	0.0	0.0
Total liabilities	164.4	196.3
Shareowners' (deficit) equity	924.9	907.3
Total liabilities and shareowners' equity (deficit)	1,089.3	1,103.6
Notes guaranteed by subsidiaries [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	1.8	2.4	2.5	1.5
Receivables, net	134.1	153.6
Other current assets	20.0	18.7
Total current assets	155.9	174.7
Property, plant and equipment, net	941.8	921.8
Investment in CyrusOne	0.0	0.0
Goodwill	2.2	2.2
Investments in and advances to subsidiaries	0.0	4.3
Other noncurrent assets	6.1	6.3
Total assets	1,106.0	1,109.3
Current portion of long-term debt	6.1	5.0
Accounts payable	46.6	32.6
Other current liabilities	42.9	42.7
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	95.6	80.3
Long-term debt, less current portion	156.0	151.9
Other noncurrent liabilities	169.6	160.5
Intercompany payables	79.5	127.3
Total liabilities	500.7	520.0
Shareowners' (deficit) equity	605.3	589.3
Total liabilities and shareowners' equity (deficit)	1,106.0	1,109.3
Notes guaranteed by subsidiaries [Member] | Consolidation, Eliminations [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.0	0.0	$ 0.0	$ 0.0
Receivables, net	0.0	0.0
Other current assets	0.0	0.0
Total current assets	0.0	0.0
Property, plant and equipment, net	0.0	0.0
Investment in CyrusOne	0.0	0.0
Goodwill	0.0	0.0
Investments in and advances to subsidiaries	(1,648.4)	(1,679.3)
Other noncurrent assets	(154.7)	(146.2)
Total assets	(1,803.1)	(1,825.5)
Current portion of long-term debt	0.0	0.0
Accounts payable	0.0	0.0
Other current liabilities	0.0	0.0
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	0.0	0.0
Long-term debt, less current portion	0.0	0.0
Other noncurrent liabilities	(154.7)	(146.2)
Intercompany payables	(117.4)	(182.0)
Total liabilities	(272.1)	(328.2)
Shareowners' (deficit) equity	(1,531.0)	(1,497.3)
Total liabilities and shareowners' equity (deficit)	$ (1,803.1)	$ (1,825.5)