Supplemental Guarantor Information - Condensed Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Condensed Consolidating Balance Sheets
Cash and cash equivalents	$ 9.6	$ 7.4	$ 14.8	$ 57.9
Other current assets	3.0	2.2
Total current assets	208.9	200.4
Property, plant and equipment, net	1,021.7	975.5
Investment in CyrusOne	27.4	55.5
Goodwill	14.3	14.3
Other noncurrent assets	18.4	17.8
Total assets	1,423.2	1,446.4
Current portion of long-term debt	14.7	13.8
Accounts payable	142.5	128.9
Other current liabilities	24.5	25.0
Other current liabilities from discontinued operations	0.6	5.4
Total current liabilities	256.9	259.2
Long-term debt, less current portion	1,125.7	1,223.8
Other noncurrent liabilities	40.1	36.6
Total liabilities	1,640.2	1,744.6
Shareowners' (deficit) equity	(217.0)	(298.2)
Total liabilities and shareowners' equity (deficit)	1,423.2	1,446.4
Notes guaranteed by parent [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	9.6	7.4	14.8	57.9
Receivables, net	157.5	157.1
Other current assets	41.8	35.9
Total current assets	208.9	200.4
Property, plant and equipment, net	1,021.7	975.5
Investment in CyrusOne	27.4	55.5
Goodwill	14.3	14.3
Investments in and advances to subsidiaries	0.0	0.0
Other noncurrent assets	150.9	200.7
Total assets	1,423.2	1,446.4
Current portion of long-term debt	14.7	13.8
Accounts payable	142.5	128.9
Other current liabilities	99.1	111.1
Other current liabilities from discontinued operations	0.6	5.4
Total current liabilities	256.9	259.2
Long-term debt, less current portion	1,125.7	1,223.8
Other noncurrent liabilities	257.6	261.6
Intercompany payables	0.0	0.0
Total liabilities	1,640.2	1,744.6
Shareowners' (deficit) equity	(217.0)	(298.2)
Total liabilities and shareowners' equity (deficit)	1,423.2	1,446.4
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	(1,673.8)	(1,555.7)
Other noncurrent assets	(161.7)	(146.3)
Total assets	(1,835.5)	(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	(161.7)	(146.2)
Intercompany payables	(43.1)	(54.7)
Total liabilities	(204.8)	(200.9)
Shareowners' (deficit) equity	(1,630.7)	(1,501.1)
Total liabilities and shareowners' equity (deficit)	(1,835.5)	(1,702.0)
Notes guaranteed by parent [Member] | Parent Company [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	7.9	4.6	8.7	56.2
Receivables, net	2.1	0.7
Other current assets	2.7	1.6
Total current assets	12.7	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	817.0	844.6
Other noncurrent assets	205.4	207.2
Total assets	1,035.5	1,059.0
Current portion of long-term debt	5.4	5.4
Accounts payable	0.6	0.7
Other current liabilities	36.9	41.6
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	42.9	47.7
Long-term debt, less current portion	935.6	1,018.6
Other noncurrent liabilities	230.1	235.5
Intercompany payables	43.1	54.7
Total liabilities	1,251.7	1,356.5
Shareowners' (deficit) equity	(216.2)	(297.5)
Total liabilities and shareowners' equity (deficit)	1,035.5	1,059.0
Notes guaranteed by parent [Member] | Cincinnati Bell Telephone Company [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.8	1.0	3.2	1.0
Receivables, net	0.0	0.0
Other current assets	21.7	20.2
Total current assets	22.5	21.2
Property, plant and equipment, net	967.7	921.5
Investment in CyrusOne	0.0	0.0
Goodwill	2.2	2.2
Investments in and advances to subsidiaries	52.0	63.9
Other noncurrent assets	2.2	3.0
Total assets	1,046.6	1,011.8
Current portion of long-term debt	6.2	5.0
Accounts payable	100.7	84.8
Other current liabilities	41.6	45.3
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	148.5	135.1
Long-term debt, less current portion	105.1	134.3
Other noncurrent liabilities	188.2	168.3
Intercompany payables	0.0	0.0
Total liabilities	441.8	437.7
Shareowners' (deficit) equity	604.8	574.1
Total liabilities and shareowners' equity (deficit)	1,046.6	1,011.8
Notes guaranteed by parent [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.9	1.8	2.9	0.7
Receivables, net	155.4	156.4
Other current assets	17.4	14.1
Total current assets	173.7	172.3
Property, plant and equipment, net	53.6	53.7
Investment in CyrusOne	27.4	55.5
Goodwill	12.1	12.1
Investments in and advances to subsidiaries	804.8	647.2
Other noncurrent assets	105.0	136.8
Total assets	1,176.6	1,077.6
Current portion of long-term debt	3.1	3.4
Accounts payable	41.2	43.4
Other current liabilities	20.6	24.2
Other current liabilities from discontinued operations	0.6	5.4
Total current liabilities	65.5	76.4
Long-term debt, less current portion	85.0	70.9
Other noncurrent liabilities	1.0	4.0
Intercompany payables	0.0	0.0
Total liabilities	151.5	151.3
Shareowners' (deficit) equity	1,025.1	926.3
Total liabilities and shareowners' equity (deficit)	1,176.6	1,077.6
Notes guaranteed by subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	9.6	7.4	14.8	57.9
Receivables, net	157.5	157.1
Other current assets	41.8	35.9
Total current assets	208.9	200.4
Property, plant and equipment, net	1,021.7	975.5
Investment in CyrusOne	27.4	55.5
Goodwill	14.3	14.3
Investments in and advances to subsidiaries	0.0	0.0
Other noncurrent assets	150.9	200.7
Total assets	1,423.2	1,446.4
Current portion of long-term debt	14.7	13.8
Accounts payable	142.5	128.9
Other current liabilities	99.1	111.1
Other current liabilities from discontinued operations	0.6	5.4
Total current liabilities	256.9	259.2
Long-term debt, less current portion	1,125.7	1,223.8
Other noncurrent liabilities	257.6	261.6
Intercompany payables	0.0	0.0
Total liabilities	1,640.2	1,744.6
Shareowners' (deficit) equity	(217.0)	(298.2)
Total liabilities and shareowners' equity (deficit)	1,423.2	1,446.4
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	(1,790.6)	(1,679.3)
Other noncurrent assets	(161.7)	(146.2)
Total assets	(1,952.3)	(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	(161.7)	(146.2)
Intercompany payables	(152.6)	(182.0)
Total liabilities	(314.3)	(328.2)
Shareowners' (deficit) equity	(1,638.0)	(1,497.3)
Total liabilities and shareowners' equity (deficit)	(1,952.3)	(1,825.5)
Notes guaranteed by subsidiaries [Member] | Parent Company [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	7.9	4.6	8.7	56.2
Receivables, net	2.1	0.7
Other current assets	2.7	1.6
Total current assets	12.7	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	817.0	844.6
Other noncurrent assets	205.4	207.2
Total assets	1,035.5	1,059.0
Current portion of long-term debt	5.4	5.4
Accounts payable	0.6	0.7
Other current liabilities	36.9	41.6
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	42.9	47.7
Long-term debt, less current portion	935.6	1,018.6
Other noncurrent liabilities	230.1	235.5
Intercompany payables	43.1	54.7
Total liabilities	1,251.7	1,356.5
Shareowners' (deficit) equity	(216.2)	(297.5)
Total liabilities and shareowners' equity (deficit)	1,035.5	1,059.0
Notes guaranteed by subsidiaries [Member] | Guarantor Subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	0.3	0.4	1.3	0.2
Receivables, net	2.1	2.8
Other current assets	18.3	15.6
Total current assets	20.7	18.8
Property, plant and equipment, net	53.3	53.4
Investment in CyrusOne	27.4	55.5
Goodwill	12.1	12.1
Investments in and advances to subsidiaries	951.6	830.4
Other noncurrent assets	101.4	133.4
Total assets	1,166.5	1,103.6
Current portion of long-term debt	3.1	3.4
Accounts payable	64.3	95.6
Other current liabilities	22.7	26.8
Other current liabilities from discontinued operations	0.6	5.4
Total current liabilities	90.7	131.2
Long-term debt, less current portion	52.0	53.3
Other noncurrent liabilities	7.0	11.8
Intercompany payables	0.0	0.0
Total liabilities	149.7	196.3
Shareowners' (deficit) equity	1,016.8	907.3
Total liabilities and shareowners' equity (deficit)	1,166.5	1,103.6
Notes guaranteed by subsidiaries [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Consolidating Balance Sheets
Cash and cash equivalents	1.4	2.4	$ 4.8	$ 1.5
Receivables, net	153.3	153.6
Other current assets	20.8	18.7
Total current assets	175.5	174.7
Property, plant and equipment, net	968.0	921.8
Investment in CyrusOne	0.0	0.0
Goodwill	2.2	2.2
Investments in and advances to subsidiaries	22.0	4.3
Other noncurrent assets	5.8	6.3
Total assets	1,173.5	1,109.3
Current portion of long-term debt	6.2	5.0
Accounts payable	77.6	32.6
Other current liabilities	39.5	42.7
Other current liabilities from discontinued operations	0.0	0.0
Total current liabilities	123.3	80.3
Long-term debt, less current portion	138.1	151.9
Other noncurrent liabilities	182.2	160.5
Intercompany payables	109.5	127.3
Total liabilities	553.1	520.0
Shareowners' (deficit) equity	620.4	589.3
Total liabilities and shareowners' equity (deficit)	$ 1,173.5	$ 1,109.3